Laser precision microprocessing of materials 9780429488771, 0429488777, 9780429949890, 0429949898, 9780429949906, 0429949901, 9780429949913, 042994991X

Table of contents :
Content: Cover
Half Title
Title Page
Copyright Page
Table of Contents
Symbols and abbreviations
Introduction
1: Overview of the present state and the development of copper vapour lasers and copper vapour laser systems
1.1. Discovery and first investigations and design of copper vapour lasers
1.2. The condition and development of CVL in Russia
1.3. The condition and development of CVL and CVLS in foreign countries
1.4. The current state and development of the CVL and CVLS in the Istok company
1.5. Conclusions and results for chapter 1 2: Possibilities of pulsed copper vapour lasers and copper vapour laser systems for microprocessing of materials2.1. The current state of the modern laser processing equipment for the processing of materials and the place in it of pulsed copper vapour lasers
2.2. Analysis of the capabilities of pulsed CVL for microprocessing of metallic and non-metallic materials
2.3 Equipment MP200X of Oxford Laser for microprocessing
2.4 The main results of the first domestic studies on microprocessing at the Kareliya CVLS and installations EM-5029 2.5 The first domestic experimental laser installation (ELI) Karavella2.6. Conclusions and results for Chapter 2
3: A new generation of highly efficient and long-term industrial sealed-off active elements of pulsed copper vapour lasers of the Kulon series with a radiation power of 1-20 W and Kristall series with a power of 30-100 W
3.1. Analysis of the first designs of self-heating AE pulsed CVLs and the reasons for their low durability and efficiency
3.2. Investigation of ways to increase the efficiency, power and stability of the output radiation parameters of CVL 3.3. Choice of directions for the development of a new generation of industrial sealed-off self-heating AE of the CVLs3.4. Appearance and weight and dimensions of industrial sealed-off AEs of the pulsed CVL of the Kulon and Kristall series
3.5. Construction, manufacturing and training technology, basic parameters and characteristics of industrial sealed-off AEs of the Kulon and Kristall CVL series
3.6. Conclusions and results for chapter 3 4: Highly selective optical systems for the formation of single-beam radiation of diffraction quality with stable parameters in copper vapour lasers and copper vapour laser systems4.1. Distinctive properties and features of the formation of radiation in a pulsed CVL
4.2 Experimental settings and research methods
4.3. Structure and characteristics of radiation of CVL in single-mirror mode. Conditions for the formation of single-beam radiation with high quality

Citation preview

Laser Precision Microprocessing of Materials

Laser Precision Microprocessing of Materials

A.G. Grigor’yants M.A. Kazaryan N.A. Lyabin

Translated from Russian by V.E. Riecansky

CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2019 by CISP CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed on acid-free paper International Standard Book Number-13: 978-1-138-59454-8 (Hardback) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright. com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com

Contents

v

Contents Symbols and abbreviations Introduction 1. 1.1. 1.2. 1.3. 1.4. 1.5. 2. 2.1. 2.2.   2.4.    2.6.

ix xi

Overview of the present state and the development of copper vapour lasers and copper vapour laser systems 1 Discovery and first investigations and design of copper vapour lasers 1 The condition and development of CVL in Russia 3 The condition and development of CVL and CVLS in foreign countries 18 The current state and development of the CVL and CVLS in the Istok company 26 Conclusions and results for chapter 1 36 Possibilities of pulsed copper vapour lasers and copper vapour laser systems for microprocessing of materials The current state of the modern laser processing equipment for the processing of materials and the place in it of pulsed copper vapour lasers Analysis of the capabilities of pulsed CVL for microprocessing of metallic and non-metallic materials (TXLSPHQW ɆɊɏ RI 2[IRUG /DVHU IRU PLFURSURFHVV ing The main results of the first domestic studies on microprocessing at the Kareliya CVLS and LQVWDOODWLRQV (0                                    7KH ILUVW GRPHVWLF H[SHULPHQWDO ODVHU LQVWDOODWLRQ (ELI) Karavella Conclusions and results for Chapter 2

41 41 43 51  55 66

vi

3.

3.1. 3.2. 3.3. 3.4. 3.5. 3.6. 4.

4.1.  4.3. 4.4.

4.5.

4.6.

Contents A new generation of highly efficient and long-term industrial sealed-off active elements of pulsed copper vapour lasers of the Kulon series with a radiation power of 1–20 W and Kristall series with a power of 30–100 W 69 Analysis of the first designs of self-heating AE pulsed CVLs and the reasons for their low durability DQG HIILFLHQF\ Investigation of ways to increase the efficiency, power and stability of the output radiation parameters of CVL 73 Choice of directions for the development of a new generation of industrial sealed-off self-heating AE of the CVLs 76 Appearance and weight and dimensions of industrial sealed-off AEs of the pulsed CVL of the Kulon and Kristall series 78 Construction, manufacturing and training technology, basic parameters and characteristics of industrial VHDOHGRII$(VRIWKH.XORQDQG.ULVWDOO&9/VHULHV  Conclusions and results for chapter 3 161 Highly selective optical systems for the formation of single-beam radiation of diffraction quality with stable parameters in copper vapour lasers and copper vapour laser systems 166 Distinctive properties and features of the formation of radiation in a pulsed CVL 17 ([SHULPHQWDO VHWWLQJV DQG UHVHDUFK PHWKRGV  Structure and characteristics of radiation of CVL in single-mirror mode. Conditions for the formation of single-beam radiation with high quality 174 Structure and characteristics of the laser radiation in the regime with an unstable resonator with two FRQYH[ PLUURUV   Conditions for the formation of single-beam radiation with diffraction divergence and stable parameters 187 Structure and characteristics of the radiation of CVL in the regime with telescopic UR. Conditions for the formation and separation of a radiation beam ZLWK GLIIUDFWLRQ GLYHUJHQFH  Investigation of the conditions for the formation of a

Contents

4.7. 4.8. 5. 5.1. 5.2. 5.3.     6 6.1. 6.2. 6.2.1. 6.2.2. 6.2.3. 6.3. 6.3.1. 6.3.2. 6.3.3.   7. 7.1.

vii

powerful single-beam radiation with a GLIIUDFWLRQGLYHUJHQFHLQD&9/6RIWKH02±3$W\SH  Investigation of the properties of the active medium of a pulsed CVL using CVLS 231 Conclusions and results for chapter 4 235 Industrial copper vapour lasers and copper vapour laser systems based on the new generation of sealed-off active elements and new optical systems The first generation of industrial CVLs A new generation of industrial CVLs of the Kulon series Two-channel Karelia CVLS with high quality of radiation 7ZRFKDQQHO ODPSSXPSHG ODVHU &9/6 .XORQ 7KUHHFKDQQHO &9/6 .DUHOLD0 3RZHUIXO &9/6 &RQFOXVLRQV DQG UHVXOWV IRU FKDSWHU 

243 243 255 274    

Modern automated laser technological installation Karavella (ALTI) 299 Requirements for pulsed CVL and CVLS in PRGHUQ WHFKQRORJLFDO HTXLSPHQW  Industrial ALTI Karavella-1 and Karavella-1M on the EDVLV RI WZRFKDQQHO &9/6  Composition, construction and principle of operation 34 Principle of construction and structure of the motion and control system 318 Main technical parameters and characteristics 323 Industrial ALTIs Karavella-2 and Karavella-2M on the basis of single-channel CVL 326 Basics of creating industrial ALTIs Karavella-2 and Karavella-2M 326 Composition, design and operation principle of ALTI  Main technical parameters and characteristics 335 &RQFOXVLRQV DQG UHVXOWV IRU &KDSWHU   Laser technologies of precision microprocessing of foil and thin sheet materials for components for electronic devices 342 The threshold densities of the peak and average radiation

Contents

viii

7.2. 7.3.  7.4. 7.5. 7.6. 8.

8.1.   8.3.      

power of CVL for evaporation of heat-conducting and refractory materials, silicon and polycrystalline diamond 343 Effect of the thickness of the material on the speed and quality of the laser treatment 347 Development of the technology of chemical cleaning of PHWDO SDUWV IURP VODJ DIWHU ODVHU PLFURPDFKLQLQJ  Investigation of the surface quality of laser cutting and the structure of the heat-affected zone 355 Development of microprocessing technology in the production of LTCC multi-layer ceramic boards for microwave electronics products 363 Conclusions and results for Chapter 7 371 Using industrial automatic laser technological installations Karavella-1, Karavella-1M, Karavella-2 and Karavella-2M for the fabrication of precision parts for electronic devices The possibilities of application of ALTI Karavella for the manufacture of precision parts ([DPSOHV RI WKH PDQXIDFWXUH RI SUHFLVLRQ SDUWV IRU electronic components at ALTI Karavella Advantages of the laser microprocessing of materials on ALTI Karavella in comparison with traditional SURFHVVLQJ PHWKRGV 3HUVSHFWLYH GLUHFWLRQV RI DSSOLFDWLRQ RI$/7, .DUDYHOOD &RQFOXVLRQV DQG UHVXOWV IRU &KDSWHU 

Conclusion References Index

373 373 378    397 401 416

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Symbols and abbreviations ± SRZHU FRQVXPHG IURP WKH UHFWLILHU RI WKH SRZHU VRXUFH ± DYHUDJH RXWSXW SRZHU ± ZDYHOHQJWK RI WKH UDGLDWLRQ ± OHQJWK RI WKH DFWLYH PHGLXP ± OHQJWK RI WKH GLVFKDUJH FKDQQHO ± OHQJWK RI WKH RSWLFDO UHVRQDWRU ± IRFDO OHQJWK RI WKH OHQV ± JDLQ RI WKH RSWLFDO UHVRQDWRU ± UDGLXV RI FXUYDWXUH RI WKH PLUURU ± WHPSHUDWXUH RI WKH GLVFKDUJH FKDQQHO ± WLPH RI SRSXODWLRQ LQYHUVLRQ H[LVWHQFH ± SXOVH GXUDWLRQ – radiation divergence ± GLIIUDFWLRQ GLYHUJHQFH RI UDGLDWLRQ ± SHDN UDGLDWLRQ SRZHU GHQVLW\ ± YROXPH RI WKH DFWLYH PHGLXP ± YROWDJH ± HQHUJ\ LQ WKH UDGLDWLRQ SXOVH

Introduction The development of the electronic industry, with the further miniaturization of electronic components and the use of new materials, puts ever-increasing demands on the quality, reliability and competitiveness of manufactured products. That, in turn, makes higher demands on the parameters of the components, thus dictating the creation of new technologies and technological processes. A special recognition was given to laser technologies for microprocessing. In this case, the function of the processing tool is performed by a highintensity focused light spot. To ensure high quality of machining, WKHWRROVKRXOGSURYLGHWKHIROORZLQJSDUDPHWHUV±PLFURQZLGWKRI FXW±—P PLQLPDOKHDWDIIHFWHG]RQH±@ 7KH VSHFWUXPRISURFHVVHGPDWHULDOVLQFOXGHVKHDWFRQGXFWLQJ±&X$O $J$X UHIUDFWRU\ ± : 0R 7D 5H DQG RWKHU PHWDOV ± 1L 7L =U )H DQG WKHLU DOOR\V VWHHO GLHOHFWULFV DQG VHPLFRQGXFWRUV ± VLOLFRQ polycrystalline diamond, sapphire, graphite, carbides and nitrides DQG WUDQVSDUHQW PDWHULDOV >   @ More than four decades after the first generation of the CVLs was by the efforts of a number of scientific teams, primarily Russia, the USA, England, Australia and Bulgaria, these lasers were established both with the basic physical principles of work and design, and specific applications in science, technology and medicine. The bulk of the research was devoted to the ‘pure’ CVL operating in D PL[WXUH RI WKH QHRQ EXIIHU JDV DQG FRSSHU YDSRXU DW D GLVFKDUJH WHPSHUDWXUH RI ±ƒ& ,Q WKH ODVW ± \HDUV UHVHDUFKHUV and developers have increased interest in its varieties operating at the same r–m MXQFWLRQV EXW DW UHODWLYHO\ ORZ WHPSHUDWXUHV ± ƒ&  DQG KLJKHU UHSHWLWLRQ UDWHV XS WR KXQGUHGV NLORKHUW]  WR lasers on copper halides (CuCl, CuBr, and CuI) and ‘hybrid’ (with the SXPSLQJRIDPL[WXUHRI+%U+&O%U2 or Cl2 and Ne), and also with ‘enhanced kinetics’ (with the addition of H 2 RU LWV FRPSRXQGV  > @ %XW RQ FRSSHU KDOLGHV DQG µK\EULG¶ &9/V ZLWKRXW DSSUHFLDEOH performance, the service life and stability of the output parameters remain relatively low for today, which is due to the instability in time of the composition and properties of the multicomponent gas PL[WXUH RI WKH DFWLYH PHGLXP $0  7KHUHIRUH WRGD\ IURP WKH point of view of industrial production and practical application, the advantage remains on the side of ‘pure’ CVLs and with ‘enhanced kinetics’. $W ORZ UDGLDWLRQ SRZHU OHYHOV ± :  WKH &9/ LV GHVLJQHG constructively as a separate generator (monoblock) with one lowpower active element (AE) and an optical resonator. To obtain WKH DYHUDJH ± :  DQG HVSHFLDOO\ KLJK XQLW RU WHQV RI N:  radiation power levels, CVLSs operating according to the master RVFLOODWRU±SRZHU DPSOLILHU 02±3$  VFKHPH ZLWK RQH RU VHYHUDO SRZHUIXO$(VDV3$VDUHXVHGZLWKDSUHDPSOLILHU35$ ORFDWHGLQ IURQWRIWKH3$,QWKH&9/RIWKH02±3$W\SHLQFRPSDULVRQZLWK the CVL operating in the single-generator mode, higher efficiency DQG WKH TXDOLW\ RI WKH RXWSXW EHDP DUH DFKLHYHG > @ 7KH &9/ UHPDLQV WKH PRVW HIILFLHQW ± HIILFLHQF\  VRXUFH for pumping lasers on solutions of organic dyes (DSL) tunable along wavelengths in the near infrared region of the spectrum, non-

Introduction

xiii

linear crystals of the %%2W\SH .'3'.'3HIILFLHQF\±  WUDQVIRUPLQJ WKH JHQHUDWLRQ RI &9/ LQWR WKH VHFRQG KDUPRQLF ± Ȝ    DQG  QP LH LQWR WKH XOWUDYLROHW UHJLRQ RI the spectrum and titanium sapphire (Al 22 3: Ti 3+), which converts generation to the near-IR region spectrum, and then with the help RI WKH QRQOLQHDU FU\VWDO ± IURP WKH ,5 UHJLRQ WR EOXH 7KH XVH RI CVL with DSL and the non-linear crystal allows us to practically cover the wavelength range from the near UV to the near IR spectral UHJLRQDQGDFFRUGLQJO\WRH[SDQGWKHODVHU¶VIXQFWLRQDOFDSDELOLWLHV Such tunable pulsed laser systems are unique and preferable for both practical and scientific spectroscopic studies and microprocessing by 89 UDGLDWLRQ >    @ A special place is occupied by the use of CVLs in combination with DSL tunable in wavelengths in high-power laser systems of the 02±3$W\SH3RZHUIXO&9/VRIWKH02±3$W\SHDUHXVHGPDLQO\LQ the isotope separation system according to AVLIS technology, which uses a difference in the absorption spectra of atoms of different isotopic composition. This progressive optical technology makes it possible to produce substances with the necessary level of enrichment and high purity for use, primarily in nuclear power engineering and PHGLFLQH >  ±  @ A promising area of development for CVL is also medicine. Multifunctional modern medical devices such as Yakhroma-Med and Kulon-Med for use in oncology, low-intensity therapy, dermatology and cosmetology, microsurgery, etc. are created on its basis. This class of equipment is the leader in laser non-ablative technologies. Laser pulses act on the body’s defects selectively, without damaging the surrounding tissue and without causing pain (anesthesia is not UHTXLUHG  >±@ In addition, CVL is used as an intensifier for the brightness of the image of microobjects, in nanotechnology, high-speed photography, for analyzing the composition of substances, in laser projection systems for imaging on large screens and in open space, in lidar installations for probing the atmosphere and sea depths, in navigation systems, water treatment, gas flow visualization, laser acceleration of microparticles, holography, forensics and entertainment industry, HWF >      ± ± @ In the technology of material processing, industrial &2 2 lasers withȜ ȝP are widely used, but such heat-conducting metals as &X$O$XDQG$JDUHQRWHIILFLHQWO\WUHDWHGZLWK&22 laser radiation DQG RWKHU LQIUDUHG ODVHUV DV WKH UHIOHFWLRQ FRHIILFLHQW H[FHHGV 

xiv

Introduction

3RZHUIXO ,5 ODVHUV DUH PDLQO\ XVHG IRU KLJKVSHHG FXWWLQJ FXWWLQJ DQGZHOGLQJRIIHUURXVPHWDOVDQGVWDLQOHVVVWHHOXSWRPPWKLFN > @ $ZLGHO\GLVWULEXWHGVROLGVWDWHODVHUEDVHGRQ\WWULXP±DOXPLQXP garnet with neodymium (1G@ i.e., they are generated in the near-UV range. This is their advantage for wide application in lithography processes in semiconductor manufacturing, in eye surgery, as well as in dermatology. However, due to the relatively large divergence and the smaller working pulse UHSHWLWLRQ IUHTXHQFLHV QRW PRUH WKDQ ± N+]  WKH TXDOLW\ DQG productivity of material processing is reduced, and this class of lasers is used mainly for the processing of plastics, ceramics, crystals, biological tissues. Diode (semiconductor) lasers are small in size and can be produced in large batches at relatively low costs. Most diode lasers JHQHUDWHLQWKHQHDU,5UHJLRQ±Ȝ ±QP7KH\DUHUHOLDEOH and durable, but the output power of a single element is limited and have a high radiation divergence. The diode lasers are used in many spheres of human activity, mainly in the telecommunications and RSWLFDO PHPRU\ VHFWRUV >   @ DQG DUH DOVR XVHG LQ ODUJH quantities as pumping sources for solid-state and fiber lasers. The developed technology of adding single diodes to diode lines allows WRLQFUHDVHWKHDYHUDJHODVHUSRZHUWR±N:ZKLFKLVHQRXJKIRU KLJKSHUIRUPDQFHDQGKLJKTXDOLW\ZHOGLQJIRUH[DPSOHDOXPLQLXP parts. The above comparative analysis of the characteristics of CVL with other known types of technological lasers confirms that the CVL remains a promising quantum device in terms of the set of radiation output parameters, primarily for the microprocessing of materials of electronic equipment and selective technologies for isotope separation, and also in spectroscopy, image brightness amplifiers, medicine and other fields of science and technology. )LJXUH , UHSUHVHQWV WKH JOREDO PDUNHW IRU ODVHU VDOHV IURP  WR)LJ,VKRZVVWUXFWXUHRIWKHZRUOGPDUNHWRIODVHUVRXUFHV UDGLDWLRQ IRU  >@ Figure I.3 presents the dynamics of the global sales volume of all types of lasers by years for the acquisition of technological HTXLSPHQW >@ 7HFKQRORJLFDOHTXLSPHQWXVHV&22, solid-state, fiber, and H[FLPHU lasers. The use of CVL in specialized equipment, in spite of the XQLTXH FRPELQDWLRQ RI LWV RXWSXW SDUDPHWHUV LV H[WUHPHO\ OLPLWHG due to the small number of commercial models on the market with

Fig. I1:RUOGZLGH VDOHV RI ODVHUV IURP  WR 

Diode

Non-diode

Total $billions

xvi

Introduction

Introduction

xvii

0DWHULDOV SURFHVVLQJ  7HOHFRPPLQXFDWLRQV  2SWLFDO PHPRU\  0HGLFLQH DQG FRVPHWLFV  Scientific studies and LQVWDOODWLRQV  'HYLFHV DQG VHQVRUV  /LWKRJUDSK\  'HSRVLWLRQ RI LPDJHV  (QWHUWDLQPHQW GLVSOD\V  Fig. I2. The structure of the world market of laser radiation sources by fields of DSSOLFDWLRQ IRU  Volume, millions of dollars

3539 2785 2101

1617

1000 1000

II

200i 2008 2009 2(H0 201l

20l2 2(J13 0014 Years

Fig. I.3. The volume of sales of lasers by years for the acquisition of technological equipment.

xviii

Introduction

high reliability and radiation quality. This situation seems to have taken shape for a number of reasons. Firstly, in many research LQVWLWXWHVRI5XVVLD8665 ODUJHVFDOHWKHRUHWLFDODQGH[SHULPHQWDO studies of physical processes in CVL were carried out, rather than LQGXVWULDO GHYHORSPHQWV >± ±@ 6HFRQGO\ LQ WKH DGYDQFHG FRXQWULHV DEURDG 86$ %ULWDLQ )UDQFH -DSDQ  WKH PDLQ HIIRUWV were directed to research and development of high-power CVLS RI WKH W\SH 02±3$ LQ SURYLGLQJ ODVHU LVRWRSH VHSDUDWLRQ SURJUDPV according to AVLIS technology for the needs of nuclear power [15, @7KXVWKHGHYHORSPHQWRIWKHPRVWSRSXODUFRPPHUFLDO &9/V ZKLFK LQFOXGH ODVHUV RI VPDOO ± :  DQG PHGLXP ± :  SRZHU OHYHOV UHPDLQHG DV LW ZHUH DORRI 7KLUGO\ RYHU WKH ODVW ± \HDUV WKH ODVHU PDUNHW ZDV UHSUHVHQWHG E\ D relatively large number of CVLs and its varieties with a low level of reliability and radiation quality, which reduced the user demand for this type of laser. Nevertheless, today it is possible to single out several organizations and firms that continue to improve the old and create new commercial models of CVLs and CVLSs and, on their basis, modern technological equipment for microprocessing of materials and isotope separation, as well as medical facilities and other equipment. They include, first of all, Istok Co. (Fryazino, Moscow region) together with VELIT (Istra, Moscow region) and Chistye Tekhnologii (Izhevsk) with the scientific support of the 31 /HEHGHY 3K\VLFDO ,QVWLWXWH RI WKH 5XVVLDQ $FDGHP\ RI 6FLHQFHV 2[IRUG /DVHUV (QJODQG  Macquarie University (Australia) and 3XOVH/LJKW%XOJDULD 7KHLawrence Livermore National Laboratory is the leader in powerful CVLSs, intended for isotope separation WHFKQRORJ\ ZKHUH WKH DYHUDJH SRZHU LV EURXJKW WR  N: DQG WKH Kurchatov Institute. Studies continue at the $13URNKRURY,QVWLWXWH RI *HQHUDO 3K\VLFV 5XVVLDQ $FDGHP\ RI 6FLHQFHV 768 DQG WKH ,QVWLWXWH RI 2SWLFV DQG $WPRVSKHUH RI WKH 6% 5$6 7RPVN  WKH ,QVWLWXWH RI 6HPLFRQGXFWRU 3K\VLFV 1RYRVLELUVN  0HNKDWURQ 6W 3HWHUVEXUJ1DWLRQDO5HVHDUFK8QLYHUVLW\RI,QIRUPDWLRQ7HFKQRORJLHV 0HFKDQLFVDQG2SWLFV Bauman Moscow State Technical University DQGWKH-RLQW,QVWLWXWHIRU+LJK7HPSHUDWXUHVRIWKH5XVVLDQ$FDGHP\ RI 6FLHQFHV 0RVFRZ  >         ±@ To realize the advantages of pulsed radiation from CVL in the technology of precision microprocessing of materials and other modern technologies, it is necessary to create a new generation of highly efficient industrial CVLs and CVLSs. The introduction of the technology of laser microprocessing in the production of electronic

Introduction

xix

components allows, in comparison with traditional methods of processing, including electroerosion mashining, to shorten the cycle of preparation of production, to order and increase the productivity, WR H[FOXGH WKH PHFKDQLFDO SUHVVXUH RI WKH WRRO DQG WKH WKHUPDO influence, to improve the quality and resource of products. This monograph is devoted to research and development aimed at creating a new generation of industrial pulsed CVLs and CVLSs with high quality and stability of radiation parameters and on their basis technological equipment and technologies for precision microprocessing of materials. The first chapter of the monograph presents a review of foreign and domestic literature on the state, development, and applications of CVLs operating in the regime of an individual oscillator and powerful CVLSs operating according to WKH HIIHFWLYH 02±3$ VFKHPH FKDSWHU  GHVFULEHV WKH SRVVLELOLWLHV of pulsed CVLs and CVLSs for microprocessing materials and the first technological installations created on their basis. The chapters ± RXWOLQH WKH UHVXOWV RI WKH ODWHVW GHYHORSPHQWV DQG UHVHDUFK LQ these areas: ±FUHDWLRQRIDQHZJHQHUDWLRQRIKLJKSHUIRUPDQFHGXUDEOHDQG stable parameters of industrial sealed-off laser AEs on copper vapour ZLWKDQDYHUDJHUDGLDWLRQSRZHURI±:2SWLPL]DWLRQRI$(LQ terms of radiation power and efficiency from power consumption, buffer gas pressure and hydrogen additives, pulse repetition frequency and pump current pulse characteristics; ±GHYHORSPHQWDQGUHVHDUFKRIKLJKO\HIILFLHQWDQGUHOLDEOHFLUFXLWV IRUWKHH[HFXWLRQRIDKLJKYROWDJHSRZHUVRXUFHPRGXODWRUZLWKWKH nanosecond duration of the pump pulses; ±UHVHDUFKDQGGHYHORSPHQWRIKLJKO\VHOHFWLYHRSWLFDOUHVRQDWRUV and systems for the formation of single-beam radiation of diffraction quality in CVL and powerful CVLSs and with stable parameters for DFKLHYLQJ KLJK SHDN SRZHU GHQVLWLHV  ± 12:FP 2); ± LQYHVWLJDWLRQ RI WKH SURSHUWLHV RI WKH DFWLYH PHGLXP RI WKH pulsed CVL and development on their basis of methods and electronic devices for on-line power control and pulse repetition frequency of radiation; ±GHYHORSPHQWRQWKHEDVLVRIDQHZJHQHUDWLRQRIVHDOHGRII$(V of new high-selective optical systems, electrical circuits and methods control of radiation parameters of industrial technological CVLs and &9/6V ZLWK WKH UDGLDWLRQ SRZHU XS WR  : ZLWK KLJK UHOLDELOLW\ efficiency, quality and stability of the radiation parameters;

xx

Introduction

± FUHDWLRQ RI PRGHUQ DXWRPDWHG ODVHU WHFKQRORJLFDO LQVWDOODWLRQ (ALTI) of the Karavella type on the basis of industrial CVLs and &9/6VDQGPRGHUQSUHFLVLRQWKUHHD[LV;@,QWKHVDPH \HDU03LOWFK97:DOWHU16ROLPHQ**RXOGDQG95%HQQHW SURGXFHGODVLQJRQPDQJDQHVHYDSRXUV>@LQ±RQFRSSHUDQG JROGYDSRXUV>@7KHEHVWUHVXOWVZHUHDFKLHYHGZLWKWKHWUDQVLWLRQV of copper atoms with emission wavelengths Ȝ DQGQP (Fig. 1.1). Large financial and material resources were spent on the research and development of effective copper vapour lasers (CVL). The first GHVLJQ RI FRSSHU DQG JROG YDSRXU ODVHUV &9/ DQG *9/  ZDV D ceramic tube made of alumina (Al223 ZLWKDQH[WHUQDOHOHFWULFKHDWHU KHDWHGWRƒ&DQGILOOHGZLWKDEXIIHUJDVRIKHOLXP>@7KHSHDN power on the green line (Ȝ QP ZLWKDSXOVHGXUDWLRQRI QVDWKDOIKHLJKW UHDFKHGN:ZLWKDQHIILFLHQF\RIRQO\ 7KH JDLQ RQ WKH JUHHQ OLQH ZDV  G%P RQ WKH \HOORZ OLQH í  G%P:KHQ D WK\UDWURQ FRPPXWDWRU LQVWHDG RI D VSDUN JDS  DQGD JDVGLVFKDUJHWXEHZLWKDGLDPHWHURIPPDQGDOHQJWKRIPP

2

Laser Precision Microprocessing of Materials Resonance levels

 QP (green)

Electronic pumping

Energy, eV

578.2 nm (yellow)

Metastable levels  *URXQG VWDWH  2S)

Fig. 1.1. Scheme of energy levels of pulsed copper vapour lasers.

were used as the power supply, the average output power of the CVL LQFUHDVHGWRP:DW+]SXOVHUHSHWLWLRQIUHTXHQF\35)  ,Q &9/V ZLWK D ODUJH FKDQQHO GLDPHWHU  PP  XQSUHFHGHQWHG SHDN SRZHU DQG HIILFLHQF\ ZHUH REWDLQHG DW WKDW WLPH  N: DQG  UHVSHFWLYHO\ > @ $W  N+] DYHUDJH SRZHU RI UDGLDWLRQ UHDFKHG :7KH ILUVW WKHRUHWLFDO DQDO\VLV RI &9/ ZDV SXEOLVKHG LQ  >@ 7KH VPDOO YDOXHV RI WKH ODVLQJ SRZHU ZHUH H[SODLQHG E\ WKH IXQGDPHQWDO OLPLWDWLRQ RI WKH LQFUHDVH LQ WKH 35) ,W ZDV EHOLHYHG WKDW WKH UHOD[DWLRQ RI WKH ORZHU ODVHU PHWDVWDEOH  OHYHOV RI PHWDO atoms occurs only on the walls of the discharge tube, where they IDOO GXH WR GLIIXVLRQ (YHQ ZLWK FKDQQHO GLDPHWHUV RI ± PP DQG HYHQ LQ WKH FDVH RI ORZ EXIIHU JDV SUHVVXUHV ± PP +J  WKH 35) FDQ QRW H[FHHG  N+] 7KH SUHVHQFH LQ WKH ODVHU GHVLJQ RI DQ H[WHUQDO KLJKWHPSHUDWXUH KHDWLQJ IXUQDFH DOVR UHGXFHG WKH efficiency and depreciated the advantages of high-efficiency lasing at r–m transitions of metal atoms. At the very beginning, CVL was used as an image brightness DPSOLILHU >@ ,Q RUGHU WR H[SDQG WKH UDQJH RI DSSOLFDWLRQV LW ZDV UHTXLUHG WR LPSURYH WKH TXDOLW\ RI LWV RXWSXW UDGLDWLRQ 6LQFH  searches have been made for optical systems forming in the CVLs

Overview of the Present State and Development of CVL

3

EHDPV ZLWK ORZ GLYHUJHQFH >@ DV D UHVXOW WKH GLYHUJHQFH RI UDGLDWLRQ KDV EHHQ UHGXFHG E\ DSSUR[LPDWHO\  WLPHV These ‘pioneering’ fundamental works of American scientists prompted an intensive study of MetVL (metal vapour lasers) in many countries of the world: the USA, Russia (USSR), England, France, $XVWUDOLD ,VUDHO %XOJDULD -DSDQ &KLQD ,QGLD HWF

1.2. The condition and development of CVL in Russia P.N. Lebedev Institute of Physics, Russian Academy of Sciences In Russia (USSR), the first successes in the study of MetVL were obtained at the 31 /HEHGHY ,QVWLWXWH RI 3K\VLFV LQ WKH 2SWLFV laboratory. In the initial period, mainly by the efforts of the staff of WKLVODERUDWRU\H[WHQVLYHVWXGLHVRIYDSRXUODVHUVRIYDULRXVPHWDOV >±±@±OHDG>±@JROG>@EDULXP>±@ PDQJDQHVH > @ FRSSHU >    @ ZHUH FRQGXFWHG In the designs of self-heating active elements (AE), ceramic tubes made of Al 22 3 were used as the gas-discharge channel, quartz tubes were used as an outer shell, cathode and anode were electrodes from flash lamp-flashes. Between the discharge channel and the shell WKHUHZDVSODFHGDILQHO\GLVSHUVHGKHDWLQVXODWRURI]LUFRQLXPR[LGH =U22 2SWLFDOZLQGRZVZHUHJOXHGWRWKHHQGVRIWKHVKHOOWKURXJK ZKLFK ODVHU UDGLDWLRQ ZDV HPLWWHG ,Q ±$$ ,VDHY 0$ .D]DU\DQ DQG ** 3HWUDVK GHPRQVWUDWHG WKH ZRUOG¶V ILUVW SXOVHG &9/)LJ ZLWKDVHOIKHDWLQJ$(ZLWKRXWDQH[WHUQDOIXUQDFH  DQGDWK\UDWURQFRPPXWDWRURIKLJKYROWDJHSXPSSXOVHV>@ZKLFK in fact predetermined in the main all the further development of this important type of laser, the most powerful in the visible region

Fig. 1.2. The first self-heating AE of the pulsed CVL.

4

Laser Precision Microprocessing of Materials

RI WKH VSHFWUXP >±@ ,Q D VHOIKHDWLQJ &9/ WKH KHDWLQJ RI WKH discharge channel with the metallic active substance to the operating temperature (T chanaƒ&  RFFXUV GXH WR WKH HQHUJ\ RI D SXOVHG periodic arc discharge, which follows with a high pulse repetition IUHTXHQF\ ZKLFK DOVR H[FLWHV FRSSHU DWRPV7KH VHOIKHDWLQJ PRGH made it possible to simplify the design of CVL and to increase its UDGLDWLRQSRZHUDQGHIILFLHQF\:LWKDGLVFKDUJHWXEHGLDPHWHURI PP D OHQJWK RI LWV KHDWHG SRUWLRQ RI  PP DQG D 35) RI ± N+] DQ DYHUDJH ODVLQJ SRZHU RI XS WR  : DQG D SHDN SRZHU RI  N: ZLWK D SUDFWLFDO HIILFLHQF\ RI a DUH REWDLQHG 3UDFWLFDO efficiency is defined as the ratio of the average output power to the HOHFWULF SRZHU FRQVXPHG IURP WKH SRZHU VRXUFH UHFWLILHU  :LWK D discharge tube diameter of 4 mm, a record specific power output RI  :FP 3  ZDV DFKLHYHG ,Q WKH ZRUN >@ WKH SRVVLELOLW\ RI obtaining high values of radiation power in CVL was demonstrated. $W WKH 35) XS WR  N+] WKH DYHUDJH UDGLDWLRQ SRZHU LQ WKH QRQ VWDWLRQDU\WKHUPDOUHJLPHRIWKH$(UHDFKHG:ZLWKDSUDFWLFDO HIILFLHQF\ RI a ,Q WKH \HDUV ± DQ XQVWDEOH UHVRQDWRU RI WKH WHOHVFRSLF W\SH ZDV VWXGLHG DW WKH ,QVWLWXWH RI 3K\VLFV RI WKH Russian Academy of Sciences in order to reduce the divergence RI WKH UDGLDWLRQ RI WKH &9/ >±@ ,Q WKH FDVH RI XVLQJ VXFK D resonator, radiation beams with a diffraction quality were formed at a magnification hundreds of times higher. At present, the main attention DQG HIIRUWV RI WKH ,QVWLWXWH RI 3K\VLFV RI WKH 5XVVLDQ $FDGHP\ RI Sciences researchers are aimed at studying various varieties of CVL, in which lasing occurs in the same r–m transitions of copper atoms. These include lasers based on copper halides (CuCl, CuBr, CuI) with additives of hydrogen (H 2  D K\EULG ODVHU &X±1H±+%U  DQG CVL with H 2, HBr, HCl additives, also called CVL with enhanced NLQHWLFV > @ )RU ODVHUV RI WKH ILUVW WZR W\SHV DQ HIILFLHQF\ RI XS WR  ZDV DFKLHYHGZLWKDQDYHUDJHODVLQJSRZHURI±:>@,Q>@ DQ DYHUDJH SRZHU RI  : DQG DQ $( HIILFLHQF\ RI  ZDV obtained for a ‘hybrid’ laser with an active medium volume of  O $( OHQJWK RI  P  DQG D  N+] 35) 7KH PDLQ UROH LQ WKH kinetics of the active medium of these lasers is played by HBr or HCl molecules, which have relatively large dissociative attachment FURVV VHFWLRQV >@ 7KH DXWKRUV EHOLHYH WKDW WKH IXWXUH OLHV EHKLQG lasers with additives, and copper bromide lasers are more promising in industrial terms in this group of lasers.

Overview of the Present State and Development of CVL

5

7KHSDSHU>@GHVFULEHVWKHLUDGYDQWDJHVRYHUµSXUH¶&9/V7KH ‘pure’ self-heating CVLs, which are widely used, operate at the GLVFKDUJH WXEH ZDOO WHPSHUDWXUHV RI ±ƒ& ZKLFK UHGXFHV the life of the AE due to the limited choice of structural elements, and have a long heating time (about 1 h). The most studied copper bromide laser has a number of potential DGYDQWDJHV LWV GLVFKDUJH WXEH WHPSHUDWXUH LV DERXW  oC lower, which makes it possible to use fused quartz. This simplifies and lowers the design of the AE, makes it possible to place the working VXEVWDQFHLQWKHH[WHQVLRQDQGUHJXODWHLWVFRQFHQWUDWLRQLQWKHDFWLYH medium, regardless of the input power, and also significantly shortens the heating time. In principle, it is possible to practically create a fully heated AE, in which there will be no limitation of the service life associated with the removal of the working substance into the ‘cold’ zones. The addition of hydrogen leads to a significant increase LQ ERWK WKH UDGLDWLRQ SRZHU DQG WKH HIILFLHQF\ XS WR  RU PRUH  +RZHYHURQHFDQQRWDJUHHZLWKDOOWKHFRQFOXVLRQVGUDZQLQ> @ 'HVSLWH WKH FRPELQDWLRQ RI WKH DERYH SRVLWLYH SURSHUWLHV WKH problem associated with the lifetime of lasers on copper halides and the preservation of high stability of the output radiation parameters remain open. In these lasers there is a more intensive consumption of the working substance, which can be due to several reasons. First, there is a deposition of copper atoms from the gas-discharge medium directly to the walls with respect to the ‘cold’ discharge tube; secondly, the copper atoms and their molecular compounds are diffused to the even ‘cooler’ AE end sections, and thirdly, the low pressure The buffer gas increases the diffusion rate of the working substance. High chemical activity of chlorine and bromine leads to an intensive (premature) destruction of the elements of the electrode assemblies and instability of the combustion of the discharge. The processes of the physico-chemical interaction of the gaseous medium with quartz and the gas evolution of quartz have also not been studied. In addition, for long-term preservation of the output radiation parameters, stabilization at the optimum level of the multicomponent composition of the active gas medium is required, in which a large number of physical processes and chemical reactions occur. For ‘clean’ CVLs, many problems related to the longevity and stability RI WKH SDUDPHWHUV KDYH DOUHDG\ EHHQ VXFFHVVIXOO\ VROYHG > @ 7KHHIILFLHQF\LQLQGXVWULDOµFOHDQ¶&9/VLV±DQGWKHDYHUDJH SRZHURXWSXWIURPRQH$(KDVUHDFKHGWKHOHYHORI±:>@

6

Laser Precision Microprocessing of Materials

It should be emphasized that the optical laboratory under the leadership of M.A. Kazaryan carried out a series of theoretical and H[SHULPHQWDOVWXGLHVRIDFWLYHRSWLFDOV\VWHPVZLWKLPDJHEULJKWQHVV DPSOLILHUVIRUPLFURREMHFWVEDVHGRQ&9/*9/gold vapour laser), BaVL (EDULXPYDSRXUODVHU HWF>@7KLVGLUHFWLRQ is unique and requires further practical development. At present, ways are being considered to increase the efficiency of CVL and the quality of its output radiation beam by using new configurations of optical systems. Much attention is paid to the use of pulsed CVL radiation for microprocessing both metallic and non-metallic PDWHULDOV >±@ In the Raman scattering laboratopy under the leadership of V.S. *RUHOLN KLJKLQWHQVLW\ SXOVHG 0HW9/V ZHUH ILUVW XVHG WR H[FLWH WKH processes of Raman, hyper-Rayleigh, and hyper-Raman scattering RI OLJKW LQ PDWWHU >@ +LJK DYHUDJH DQG SHDN SRZHU DQG 35) nanosecond pulses of MetVL turned out to be crucial for the analysis of inelastic light scattering spectra of many substances previously XQDYDLODEOHIRUDQDO\VLV$QHZXQLTXHGHYLFH±DPROHFXODUDQDO\]HU FKDUDFWHUL]HG E\ KLJK VHQVLWLYLW\ >@ ± ZDV FUHDWHG QQ WKH EDVLV RI &9/ DQG *9/ ZLWK WKH XVH RI VHDOHGRII $( RI ORZ SRZHU of the series ‘Kulon’ produced by the ,VWRN FRPSDQ\ > @  7KHRUHWLFDO DQG H[SHULPHQWDO VWXGLHV RI WKLV ODERUDWRU\ RIIHU JUHDW opportunities for the effective use of modern laser technology as a means of molecular monitoring of technological processes and for non-destructive testing of water, liquid and solid fuel, food, pharmaceutical and biological objects, determination of the molecular composition of gasoline and oil, biologically dangerous objects in IRRG DQG HQYLURQPHQW GHWHFWLRQ RI HVSHFLDOO\ GDQJHURXV DQG WR[LF substances. The A.M. Prokhorov General Physics Institute, the Russian Academy of Sciences In the Laboratory of macrokinetics of non-equilibrium processes XQGHU WKH VFLHQWLILF VXSHUYLVLRQ RI *$ 6KDIHHY D ODUJH DPRXQW RI UHVHDUFKKDVEHHQFDUULHGRXWRYHUWKHSDVW\HDUVRQWKHIRUPDWLRQ RI PHWDO QDQRSDUWLFOHV LQ OLTXLGV XVLQJ SXOVHG ODVHU UDGLDWLRQ >± @7KH SURFHVV RI IRUPDWLRQ RI QREOH PHWDO QDQRSDUWLFOHV ± JROG $X  DQG VLOYHU $J  LQ WKH DEODWLRQ RI PHWDO WDUJHWV LQ OLTXLGV ± water (H 22  DQG HWKDQRO & 2 H 5 2+  ± XVLQJ &9/ UDGLDWLRQ ZDV H[SHULPHQWDOO\VWXGLHGLQ5HI>@,QWKHZRUN>@WKHG\QDPLFV of formation of an alloy of gold and silver nanoparticles under laser

Overview of the Present State and Development of CVL

7

LUUDGLDWLRQRIDPL[WXUHRILQGLYLGXDOQDQRSDUWLFOHVZDVVWXGLHGDQG the factors influencing the formation of an alloy were determined. Individual nanoparticles were obtained by ablating metals in a liquid ZLWK UDGLDWLRQ ZLWK D ZDYHOHQJWK RI  QP ,W LV VKRZQ WKDW WKH size of the nanostructures essentially depends on the duration of the laser pulse and the power density in the beam focusing spot. The authors of the works assert that the investigated processes can undoubtedly find wide application in photonics, medicine and biology. In the Scientific Centre of Laser Materials and Technologies, under the guidance of A.A. Sobol, it was established that the technique for recording Raman spectra at high temperatures is also applicable to the study of the luminescence of atoms and individual molecular groupings in vapours over superheated melts of certain compounds >@ 7KLV WHFKQLTXH ZLWK WKH XVH RI ODVHU UDGLDWLRQ LV HIIHFWLYH IRUVWXG\LQJWKHV\QWKHVLVRIODVHUPDWHULDOVIRUH[DPSOHQRQOLQHDU optical crystals based on barium borate (BaB22 4). Synthesis of lowintensity ȕ-phase BaB 22 4 is carried out from a multicomponent melt of the Na22±%D2±%D223 system. The luminescence of atomic sodium H[FLWHGE\WKH\HOORZQP HPLVVLRQOLQHRIWKHDWRPLFOLWKLXP in vapour over superheated melts of the Na 22±%D2±%D 22 3 system and the Na2:2 4 melt was detected. It is shown that the spectrum of WKHVRGLXPGRXEOHWFDQEHUHFRUGHGXSRQH[FLWDWLRQE\WKHQP line of CVL in vapours of any superheated melts containing sodium. ,Q DOO H[SHULPHQWDO VWXGLHV LQ WKH SXOVHG &9/V WKH LQGXVWULDO sealed AEs of the Kulon series produced by the Istok company were XVHG> @ Tomsk State University (TSU) and Institute of Atmospheric Optics of the Siberian Branch of the Russian Academy of Sciences In parallel with the 31 /HEHGHY ,QVWLWXWH RI 3K\VLFV 7KH 7RPVN 6WDWH 8QLYHUVLW\ 768  DQG WKH ,QVWLWXWH RI $WPRVSKHULF 2SWLFV ,$3 7RPVN  PDGH D JUHDW FRQWULEXWLRQ WR WKH GHYHORSPHQW RI self-heating pulsed MetVLs at r–m junctions. The works of these FROOHFWLYHVXQGHUWKHVFLHQWLILFVXSHUYLVLRQRI$16ROGDWRYDQG*6 (YWXVKHQNR DUH SUHVHQWHG LQ >     @ ,Q WKH\HDUV ±VHOIKHDWLQJ&9/VRIWKH0LODQVHULHVDQGWKHQ0DODFKLWH type CuBr lasers with sealed AEs and on their basis medical, lidar DQGQDYLJDWLRQV\VWHPVV\VWHPVIRUVKRZHQWHUWDLQPHQW> ±@ZHUHFRQVWUXFWHG7KHGHVLJQRIWKH$(RIWKH &9/ DQG *9/ LV D TXDUW] WXEH DV DQ H[WHUQDO YDFXXPWLJKW VKHOO

8

Laser Precision Microprocessing of Materials

LQVLGHRIZKLFKDFHUDPLFGLVFKDUJHFKDQQHOPDGHRIEHU\OOLXPR[LGH %H2  RU DOXPLQD $O 22 3  LV FRD[LDOO\ LQVWDOOHG7KH VSDFH EHWZHHQ WKH FKDQQHO DQG WKH VKHOO LV ILOOHG ZLWK D WKHUPDO LQVXODWRU RI =U2 2. In a CuBr laser, discharge tubes are also made of quartz. The average UDGLDWLRQ SRZHU RI WKH GHYHORSHG &9/ LV ±: *9/ ± XS WR  : ZLWK 35) ± N+] SRZHU FRQVXPSWLRQ ± N: HIILFLHQF\ a  UHDGLQHVV WLPH ± PLQ WKH VHUYLFH OLIH LV ± KV ,Q ZRUNV >     @ WKH DFKLHYHPHQWV DQG UHFRUGV in MetVL are presented and they are the following. Addition of molecular hydrogen (H 2 ) to CVL leads to a significant increase LQ WKH ODVLQJ HIILFLHQF\ ± XS WR  ,Q WKH FRQWUROOHG LRQL]DWLRQ PRGH RI WKH DFWLYH PHGLXP WKH &9/ KDV DQ HIILFLHQF\ RI  ,Q WKH µSXUH¶ &9/ WKH 35) LV  N+] LQ WKH *9/ LW LV  N+]$ UHFRUG VSHFLILF DYHUDJH UDGLDWLRQ SRZHU ZDV DFKLHYHG LQ WKH 35) UDQJH RI ± N+] IRU 33, ± :FP 3 IRU &9/ DQG ± : cm 3 IRU *9/ 7KH PD[LPXP 35)V ZHUH REWDLQHG LQ D CuBr laser with hydrogen and independent preheated CuBr vapour generators WKDW DPRXQWHG WR ± N+] DQG  N+] ,W LV SUHGLFWHG WR UHFHLYH 35) PRUH WKDQ  N+] >  @ ,Q ODVHUV ZLWK hydrogen, high efficiency values are achieved, and the duration of the radiation pulses increases. The increase in the pulse duration, in the case of an unstable resonator of the telescopic type, in turn leads to an increase in the power in the beam of diffraction quality. The AE designs with spatially separated active media are proposed and implemented, allowing lasing simultaneously on several metals. Multicolour radiation is obtained in three to seven r–m transitions for YDULRXVFRPELQDWLRQVRIDWRPV&X$X&X%D3EHWF,QWKH process of accomplishing the tasks of atmospheric optics, specific requirements for MetVL were developed and lasers for atmospheric SURELQJZHUHGHYHORSHG7KHVPDOOVL]HG&9/DQG*9/ZHUHXVHG as a basis in the development of visual navigation systems for wiring and landing aircraft in conditions of reduced visibility such as Liman DQG 5DGXJD >@ Despite a number of advantages of the CuBr laser in comparison with the pure CVLs, nevertheless, today they are inferior to CVLs both in reliability and in the stability of output radiation parameters, which limits their application in practical medicine and in the technology of microprocessing of materials.

Overview of the Present State and Development of CVL

9

Establishment of the Russian Academy of Sciences ‘Joint Institute for High Temperatures of the Russian Academy of Sciences’ ,QDPRQRJUDSKµ/DVHUVRQVHOIWHUPLQDWLQJWUDQVLWLRQVRIPHWDO atoms’ was published in two volumes, edited by V.M. Batenin, where D JURXS RI VFLHQWLVWV RI WKH -RLQW ,QVWLWXWH IRU +LJK 7HPSHUDWXUHV RI WKH 5XVVLDQ$FDGHP\ RI 6FLHQFHV SURYLGH H[WHQVLYH GDWD RQ WKH entire class of pulsed MetVLs, of which a large proportion falls on WKH &9/ > @ 1 ,Q WKH ILUVW YROXPH >@ PHWKRGV IRU FUHDWLQJ DFWLYH 0HW9/ PHGLD DQG WKHLU YDULRXV H[FLWDWLRQ FRQGLWLRQV DUH FRQVLGHUHG DQG much attention is paid to the description of AE structures operating DW KLJK WHPSHUDWXUHV RI WKH GLVFKDUJH FKDQQHO ±ƒ&  7KH UHVXOWVRIERWKWKHRUHWLFDODQGH[SHULPHQWDOUHVHDUFKDQGGHYHORSPHQW are presented in detail. The basic physical processes responsible for creating population inversion in lasers on the transitions of metal atoms are discussed. The book occupies a special place in the study of plasma parameters and discharge characteristics, analyzing their interrelation with the energy, time, and other characteristics of laser UDGLDWLRQ >±@ 7KH VHFRQG YROXPH >@ GHDOV QRW RQO\ ZLWK SXUH PHWDO YDSRXU lasers, but with their chemical compounds (halides), as well as the possibility of achieving the limiting parameters of laser radiation >   @ 7KH UHVXOWV RI H[SHULPHQWDO VWXGLHV RI UDGLDWLRQ FKDUDFWHULVWLFV DW KLJK 35)V DUH SUHVHQWHG ,Q WKH &9/ ZLWK WKH GLDPHWHU DQG OHQJWK RI WKH GLVFKDUJH FKDQQHO RI  DQG  PP UHVSHFWLYHO\  N+] 35) WKH VSHFLILF DYHUDJH SRZHU RXWSXW RI  :FP 3HIILFLHQF\a ZDVREWDLQHG7KHSK\VLFVRIWKHH[FLWDWLRQ of metal vapours by electron beams generated by a free discharge is discussed. 7KH VWXGLHV >  @ GHVFULEH D PHWKRG IRU LQFUHDVLQJ WKH peak power in a radiation pulse using multipass amplifiers. Increase in peak power is achieved due to a decrease in the duration of the pulses of radiation of the master oscillator. The master oscillator and SRZHUDPSOLILHUXVHVHDOHG$(VRQFRSSHUYDSRXU*/IURPWKH Kristall series produced by the Istok Company. Efforts are also being made to efficiently convert the visible radiation of CVL to ultraviolet using non-linear crystals such as '.'3 DQG %%2 DQG KLJK UHVXOWV KDYH EHHQ DFKLHYHG > ±@ 7KH &9/V VXSSOHPHQWHG E\ D QRQOLQHDU IUHTXHQF\ FRQYHUWHU KDYH DQ H[WHQGHG HPLVVLRQ UDQJH Ȝ DQGQP:LWKD%%2FU\VWDODQDYHUDJH 1

The two volumes are available in English from CRC Press.........data to be added

10

Laser Precision Microprocessing of Materials

UDGLDWLRQ SRZHU RI  : DQG DQ RSWLFDO HIILFLHQF\ RI  ZHUH obtained with the generation of the total frequency with a wavelength Ȝ   QP ZLWK D '.'3 RI  : DQG  UHVSHFWLYHO\ :KHQ generating second harmonics using %%2 WKH IROORZLQJ EHVW UHVXOWV ZHUH DFKLHYHG  : DQG  DW Ȝ   QP DQG  : DQG  DW Ȝ   QP 7KH UHVXOWV RI WKH F\FOH RI H[SHULPHQWDO VWXGLHV RI QRQOLQHDU frequency transformations of the laser radiation with an unstable resonator were used in the Velit Company when developing a SURWRW\SHRIWKH.XORQ&X89LQGXVWULDOODVHUJHQHUDWLQJSXOVHG UDGLDWLRQLQWKHYLVLEOHDQGXOWUDYLROHWUDQJHV>±@7KHXVHRI lasers and amplifiers on copper vapour in combination with non-linear crystals is of great practical interest, since their capabilities in the field of spectroscopic research, microprocessing and nanotechnology DUH JUHDWO\ H[SDQGHG The Kurchatov Institute Russian Scientific Centre, Medical Sterilization Systems Organisation, Institute of Semiconductor Physics At the Kurchatov Institute (Moscow), Medical Sterilization Systems 2UJDQLVDWLRQ .KLPNL 0RVFRZ 5HJLRQ  DQG WKH Institute of 6HPLFRQGXFWRU 3K\VLFV ,)3 1RYRVLELUVN  SRZHUIXO WHFKQRORJLFDO systems have been developed for laser isotope separation. The systems are used mostly for the needs of nuclear energy and PHGLFLQH 7KLV FODVV RI FRPSOH[HV HPSOR\V KLJKO\ HIILFLHQW FRSSHU vapour laser systems (CVLS) operating according to the master RVFLOODWRU±SRZHU DPSOLILHU VFKHPH ZKLFK DUH GHVLJQHG IRU RSWLFDO pumping of wavelength tunable dye solution lasers (DSL). The DSL DOVRRSHUDWHDFFRUGLQJWRWKHRVFLOODWRU±SRZHUDPSOLILHUVFKHPHDQG the composition of its organic dye is determined by the necessary wavelength tuning range. The electrical circuit of the high-voltage modulators of nanosecond pulses of the pump source of the power VRXUFH 36  RI WKH &9/6 LV PDGH DQG RSWLPL]HG DFFRUGLQJ WR WKH effective scheme of capacitive voltage doubling and with two links of magnetic compression in which high-power pulsed hydrogen WK\UDWURQVRIWKHW\SH7*DUHXVHGDVFRPPXWDWRUV>@ Emitters in the CVLS are industrial sealed self-heating AEs of WKH VHULHV .ULVWDOO */ $ */% DQG */& GHVLJQDWLRQ according to the Technical Instruction (TI)) with an average radiation SRZHU RI   DQG  : UHVSHFWLYHO\ SURGXFHG E\ WKH Istok &RPSDQ\ )U\D]LQR 0RVFRZ 5HJLRQ  >  @ 7KH PDVWHU

Overview of the Present State and Development of CVL

11

RVFLOODWRULQWKH&9/6LVXVXDOO\UHSUHVHQWHGE\WKH$(PRGHOV*/ $RU*/%ZLWKDQXQVWDEOHUHVRQDWRURIWKHWHOHVFRSLFW\SHRU ZLWKRQHFRQYH[PLUURUWKHSRZHUDPSOLILHULQWKHIRUPRI*/% DQG*/&)RUH[DPSOHLQWKHV\VWHPRIWKH.XUFKDWRY,QVWLWXWH WKH PDVWHU RVFLOODWRU LV $( */% ZLWK RQH FRQYH[ PLUURU DQG WKHSRZHUDPSOLILHUKDVWZR$*&$(VWKHDYHUDJHSRZHUOHYHO LV  : DQG WKH RSWLFDO FRQYHUVLRQ FRHIILFLHQW RI WKH '6/ RI WKH \HOORZ±JUHHQSXPSHPLVVLRQVSHFWUXPȜ DQGQP LQWKH QHDU,5 UDGLDWLRQ UHDFKHV XS WR  The results of their studies of the last period have been presented by these teams mainly at All-Russian (international) scientific FRQIHUHQFHV µ3K\VLFDO DQG FKHPLFDO SURFHVVHV LQ WKH VHOHFWLRQ RI DWRPV DQG PROHFXOHV¶ >   ±@ Design Bureau of the P.N. Lebedev Institute Physics of the Russian Academy of Sciences. The Design Bureau (DB) of the 31/HEHGHY,QVWLWXWHRI3K\VLFVWKH5XVVLDQ$FDGHP\RI6FLHQFHV (Troitsk, Moscow Region), with the technical support of the Istok &RPSDQ\XQGHUWKHVFLHQWLILFVXSHUYLVLRQRI,93RQRPDUHYGHVLJQHG and constructed a modern, highly efficient and reliable medical device ±@7KH commutator in the high-voltage power source of the CVL is a pulsed K\GURJHQ WK\UDWURQ Ɍ*, ZLWK D JXDUDQWHHG OLIHWLPH RI PRUH WKDQ  KRXUV WKH JDV GLVFKDUJH WXEH ± DQ LQGXVWULDO VHDOHGRII VHOIKHDWLQJ$(RIWKH.XORQ*/&VHULHVGHVLJQDWLRQDFFRUGLQJ WR 7,  ZLWK DQ DYHUDJH UDGLDWLRQ SRZHU RI ± : DQG D PLQLPXP RSHUDWLQJWLPHRIDWOHDVWKRXUVSURGXFHGE\WKHIstok Company >  @ 7KH PHGLFDO IDFLOLW\ Yakhroma-Med is the leader in non-ablative technologies and is optimal for removing vascular, pigmented and unpainted skin defects, treating acne, smoothing out ZULQNOHV LH LQ GHUPDWRORJ\ DQG FRVPHWRORJ\ 3XOVHG UDGLDWLRQ RI WKH&9/ZLWKZDYHOHQJWKVȜ DQGQP35)RI±N+] DQG SXOVH GXUDWLRQ RI ± QV VHOHFWLYHO\ FRDJXODWHV VNLQ GHIHFWV without damaging the surrounding tissue and without causing pain ZLWKRXWDQHVWKHVLD 7KHGHYLFHLVXVHGLQPRUHWKDQFOLQLFVLQ Russia and abroad. Research Institute of Precision Engineering (PE) and Mekhatron Scientific and Production Organisation ,Q WKH V WKH 3( VWXGLHG H[WHQVLYHO\ WKH XVH RI SXOVHG &9/ radiation in the field of projective microscopy, thin film processing,

12

Laser Precision Microprocessing of Materials

and obtaining of microcircuits for a specified program, repair and fine-tuning the passive elements of microcircuits and local annealing RI LPSODQWHG SODWH VXUIDFHV IRU LQWHJUDWHG FLUFXLWV 2Q WKH EDVLV RI WKHVH VWXGLHV WHFKQRORJLFDO HTXLSPHQW RI WKH /XFK W\SH ZDV developed using the first generation of industrial sealed-off AEs of the pulsed CVL produced by the Istok Company (AE Kriogen UL .YDQW 8/ DQG .ULVWDOO */  >±@ %XW VLQFH WKH VIRUREMHFWLYHUHDVRQVWKLVGLUHFWLRQZDVQRWIXUWKHUGHYHORSHG $ W  W K D W  W L P H   7 K H  0 H N K D W U R Q  6 F L H Q W L I L F  D Q G  3 U R G X F W L R Q 2UJDQLVDWLRQ ZDV HVWDEOLVKHG RQ WKH EDVLV RI WKH 70 5HVHDUFK ,QVWLWXWH DQG WRGD\ WKLV HQWHUSULVH KDV PDQ\ \HDUV RI H[SHULHQFH LQ FUHDWLQJ PHWDO YDSRXU ODVHUV &9/ DQG *9/ G\H ODVHUV ZLWK &9/ SXPSLQJ2QHRIWKHPDLQDFWLYLWLHVRI0HNKDWURQLVWKHGHYHORSPHQW and production of laser medical systems of the Metalaz-M series for photodynamic therapy. The systems have successfully passed technical and clinical trials, which resulted in the permission of the Russian Ministry of Health for their serial production and clinical use in oncology. The second area of activity is the advertising and information systems Metalaz-R. The settings of this series are intended for laser show and advertising. Due to the combination of their energy characteristics, they allow to generate dynamic JUDSKLFDQGWH[W LQIRUPDWLRQRIKLJKEULJKWQHVVDQGVL]HVRQYDULRXV scattering surfaces (http: //18236/ru.all.biz). St. Petersburg State Polytechnic University $ JURXS RI H[SHUWV DW WKH 3RO\WHFKQLF 8QLYHUVLW\ RI 6W 3HWHUVEXUJ under the scientific and technical guidance of Yu.M. Mokrushin, GHYHORSHG&9/VZLWKDQDYHUDJHUDGLDWLRQSRZHURI:DQGKLJKHU DWN+]35)7KHFRPPXWDWRUVLQWKHKLJKYROWDJHSRZHUVRXUFHRI WKH ODVHU DUH SXOVHG K\GURJHQ WK\UDWURQV RI WKH W\SH Ɍ*, Ɍ*, DQG Ɍ*,± >@ LQ WKH UDGLDWRU ZLWK DQ unstable telescopic resonator there are industrial sealed-off AEs of WKH.ULVWDOO*/$VHULHVZLWKDSRZHURI:DQG*/&ZLWK D SRZHU RI  ZDWWV SURGXFHG E\ WKH ,VWRN &RPSDQ\ >  @ For many applications, in particular, the tasks of transmitting and converting optical information, when creating full-colour images it is necessary to have three primary colours. In the red region of the spectrum a gold vapour laser can be used successfully. As for the blue region of the spectrum, on the basis of the CVL, this group used an CVL to construct a powerful tunable laser system that can ILOO WKH H[LVWLQJ JDS DQG LW VHHPV YHU\ SURPLVLQJ >  

Overview of the Present State and Development of CVL

13

 @ 7ZRVWHS WUDQVIRUPDWLRQ RI \HOORZ±JUHHQ UDGLDWLRQ RI D SXOVHSHULRGLF&9/XVLQJDQĮ$O223:Ti+3 laser and a non-linear %%2 FU\VWDOLQWKHEOXHUHJLRQRIWKHRSWLFDOVSHFWUXPZDVH[SHULPHQWDOO\ UHDOL]HG:LWK DQ DYHUDJH PHDQ UDGLDWLRQ SRZHU RI &9/ RI :  DQ DYHUDJH JHQHUDWLRQ SRZHU RI : DW D ZDYHOHQJWK Ȝ   QP ZDVDWWDLQHGDWD35)RI+]DQGDSXOVHGXUDWLRQRIQV> @7KLVUHVXOWDOORZVRQHWRH[SHFWWRREWDLQODUJHSRZHUOHYHOVLQ the blue region of the spectrum when using more powerful CVLs to pump radiation. In the framework of this work, preliminary studies were carried out to create a colour television projection system for ODUJHVFUHHQV>@7KHSURSRVHGODVHUV\VWHPPDNHVLWSRVVLEOHWR obtain a higher spatial resolution than in the case of a solid-state 1G@ $Q DQDO\VLV RI WKH UHVXOWV RI H[SHULPHQWDO DQG WKHRUHWLFDO VWXGLHV VKRZV WKDW LQ RUGHU WR HQVXUH the conversion efficiency of the visible radiation of CVL into the UV UHJLRQ RI WKH VSHFWUXP HIILFLHQF\ ±  LW LV QHFHVVDU\ — use in an emitter of an unstable resonator of a telescopic type ZLWK DQ LQFUHDVH RI ± WLPHV — application of AE on copper vapour with a uniform distribution of the gain over the cross section of the active medium; — use as a non-linear medium of %%2 DQG F/%2 FU\VWDOV — the use of anamorphic optical systems that make it possible to form a radiation beam with a divergence less than the crystal synchronization angle, which makes it possible to provide a higher radiation power density in this crystal and a high efficiency of nonlinear frequency conversion. The fulfillment of these conditions made it possible to obtain in WKHODVHUV\VWHP89UDGLDWLRQZLWKDSRZHURI:DWDZDYHOHQJWK Ȝ   QP RSHUDWLQJ DFFRUGLQJ WR WKH VFKHPH ZLWK RQH$( */ $DQG:DFFRUGLQJWRWKHPDVWHURVFLOODWRU±SRZHUDPSOLILHU scheme. In both cases, the efficiency of non-linear frequency FRQYHUVLRQ ZDV DERXW  2QHRIWKHDSSOLFDWLRQVRIWKHFUHDWHG89V\VWHPZLWKFRQWURORI the radiation of CVL is the treatment of various materials. Another promising direction for the yellow-green emission spectrum of CVL, which was realized by the scientific and technical staff of the university, is the formation and controlled transfer of images into WKH H[WHUQDO VSDFH IRU H[DPSOH WR FORXGV DQG ODUJH REMHFWV

14

Laser Precision Microprocessing of Materials

VELIT Research and Production Enterprise (Istra, Moscow Region) is one of the leaders in the field of high-voltage engineering, in particular, in the field of development and serial production of D ZLGH UDQJH RI SRZHU VXSSOLHV IRU ;UD\ V\VWHPV 2YHU WKH SDVW  \HDUV WKH KLJKO\ UHOLDEOH KLJKYROWDJH SXOVH SRZHU VRXUFHV36  ZLWKKLJKWHFKQLFDOH[SHUWLVHKDYHEHHQFUHDWHGDQGLQYHVWLJDWHGE\ WKHJURXSRIKLJKFODVVVSHFLDOLVWVFRPSRVHGRI9*)LOLSSRY ±   @ In the VELIT Enterprise the generators of nanosecond pulses developed by the VELIT and industrial sealed-off self-heating AEs */ 9 ' * , .33* ± 78  SURGXFHG E\ WKH ,VWRN &RPSDQ\ >@ ZHUH XVHG WR GHYHORSH KLJKHIILFLHQF\ LQGXVWULDO0HW9/RIWKH.XORQVHULHV @ 7KH ODVHUV .XORQ      DUH VWUXFWXUDOO\ H[HFXWHG in the form of a monoblock. To date, several tens of these systems have been produced. 7KH.XORQ&9/KDVWZRPRGLILFDWLRQV±.XORQ&X0ZLWK VHDOHG VHOIKHDWLQJ $( */( ZLWK DYHUDJH SRZHU RI  : DQG .XORQ&X0ZLWK$(*/,ZLWKDSRZHURI:>@ The main advantage of these CVLs is the possibility of high-speed packet and pulse modulation, which allows to control the power FKDUDFWHULVWLFVE\DQ\JLYHQDOJRULWKPIURPDQ,%03&0RGXODWLRQ is achieved due to time delays in the AE of an additional current pulse, generated by a special low-power generator, relative to the PDLQ SXPS FXUUHQW SXOVH >     @ 7KLV

Overview of the Present State and Development of CVL

15

advantage provides ample opportunities for the use of the CVL in technological and medical equipment and scientific research [165,     @ 7KH &9/ .XORQ&X0 ZDV XVHG LQ LQ the Lasers and apparatus TM (Zelenograd, Moscow) in constructing two laser models ML1-2 for high-quality drilling of microholes. ,Q ± WKH Istok Company used the Kulon-15Cu-M CVL to construct automated laser technological installations (ALTU) of the type Karavella-2 and Karavella-2M for efficient precision microprocessing of thin sheet metal and non-metallic materials of ET products. A multifunctional laser medical device Kulon-Med was developed and certified. The .XORQ0HG XQLW FRPELQHV .XORQ&X0 &9/ ZLWK ZDYHOHQJWKV RI  DQG  QP DQG '6/ WXQDEOH RYHU ZDYHOHQJWKV LQ WKH UDQJH RI ± QP ,W LV LQWHQGHG IRU WKH treatment of oncological and non-oncological diseases by the method of photodynamic therapy, low-intensive therapy, in surgery, GHUPDWRORJ\ FRVPHWRORJ\ HWF >    @ 7KH .XORQ&X0 &9/ DQG QRQOLQHDU FU\VWDOV VXFK DV '.'3 and %%2 ZHUH XVHG WR FUHDWH D GHYLFH ZLWK WKH JHQHUDWLRQ RI second harmonics and total frequency in the ultraviolet region of WKHVSHFWUXP±.XORQ&X89ZLWKZDYHOHQJWKVȜ DQG QPDQGDQDYHUDJHUDGLDWLRQSRZHURI±:ZKLFKH[SDQGV WKH SUDFWLFDO FDSDELOLWLHV RI &9/ >±@ $WSUHVHQWDQDLUFRROHGFRPSDFWORZSRZHU&9/ZLWK±N+] 35)DQGDQDYHUDJHSRZHURI±:LVEHLQJGHYHORSHGZKLFKLV the basis of a spectral molecular analyzer for operational diagnostics of the composition of liquid, solid, and gaseous substances. The principal electrical circuit and design of a high-voltage current of nanosecond current pulses for pumping a two-channel CVLS on the EDVLVRIVHDOHGRII$(*/$DQG%.ULVWDOOVHULHV RSHUDWLQJ DFFRUGLQJ WR WKH PDVWHU RVFLOODWRU±SRZHU DPSOLILHU VFKHPH ZLWK D channel synchronization accuracy not worse than ±2 ns, is being worked out. The average radiation power of the CVLS should be ±:ZLWKD35)RI±N+]7KHSXUSRVHRIWKHODVHUV\VWHP of this power level is to complete the Karavella process units for SUHFLVLRQ PLFURSURFHVVLQJ RI PHWDOOLF PDWHULDOV ± PP WKLFN Chistye tekhnologii (Clean Technologies) Company (Izhevsk) GHYHORSHG VLQFH  PRGHUQ WZRFKDQQHO KLJKYROWDJH LPSXOVH transistor power source, intended for pumping CVLS, working under WKHPDVWHURVFLOODWRU02 ±SRZHUDPSOLILHU3$ VFKHPH7KH02

16

Laser Precision Microprocessing of Materials

DQG3$$(XVHWKHVHULHV.XORQ$(V*/(DQG*/,ZLWKDQ DYHUDJH UDGLDWLRQ SRZHU RI  DQG : UHVSHFWLYHO\ SURGXFHG E\ the ,VWRN&RPSDQ\>@7KHWZRFKDQQHOSRZHU source consists of a control rack and two high-voltage magnetic modulators with bias current sources. The modulators provide the JHQHUDWLRQ RI FXUUHQW SXOVHV ZLWK DQ DPSOLWXGH RI ±$ DQG D GXUDWLRQRIQRPRUHWKDQQVZLWKDSXOVHYROWDJHRI!15 kV and D35)RI±N+]DQGV\QFKURQL]DWLRQRIWKH02DQG3$FKDQQHOV ZLWKDQDFFXUDF\RI“QV7KHPD[LPXPRXWSXWSRZHURIWKHODVHU EHDPLQWKHODVHULVPDLQWDLQHGLQWKHDXWRPDWLFPRGH2QWKHEDVLV RI &9/6 ZLWK WZRFKDQQHO WUDQVLVWRU RI WKH 36 WKH Istok Company developed two models used by ALTU: Karavella-1 and Karavella-1M for precision microprocessing of metallic and non-metallic materials XS WR  DQG  PP LQ WKLFNQHVV IRU HOHFWURQLF HTXLSPHQW Lazery i apparatura TM (Laser and apparatus TM) (Zelenograd, 0RVFRZ  KDV PRUH WKDQ  \HDUV RI H[SHULHQFH LQ WKH PDUNHW DQG is today the acknowledged leader among Russian manufacturers of laser processing equipment. Under the scientific and technical JXLGDQFHRI/*6DSU\NLQWKHFHQWUHGHYHORSVPRGHUQWHFKQRORJLFDO systems for precision machining, marking and engraving, cutting and cutting, welding, fitting resistors, etc., that successfully work at electronic, nuclear, aviation, space, instrument-making, defense DQG RWKHU LQGXVWULHV 5HFHQWO\ FRPSOH[HV GHYHORSHG RQ WKH QHZHVW solid-state and fiber lasers with diode pumping and the output power of hundreds and thousands of watts and kinematic systems on linear motors have been mastered in mass production for high-performance and high-quality precision processing of various materials with a WKLFNQHVV RI ± PP To date, a laser model ML1-2 for precision microprocessing of IRLO DQG WKLQ PDWHULDOV KDV EHHQ GHYHORSHG DW WKH 13& RQ WKH EDVLV RI SXOVHG &9/ ZLWK QDQRVHFRQG GXUDWLRQ µ.XORQ&X0¶ ZLWK radiation modulation. It is recommended, if necessary, to form a WUHDWPHQW VSRW RI ± PLFURQV LQ VL]H DQG DFKLHYH D PLQLPXP WKHUPDO H[SRVXUH ]RQH Research in the Bauman Moscow State Technical University. The MSTU practically from the moment of the appearance of the first domestic lasers, carried out a large volume of theoretical and H[SHULPHQWDO VWXGLHV RI SK\VLFDO SURFHVVHV RQ WKH LQWHUDFWLRQ RI laser radiation with various materials and determination of areas of WHFKQRORJLFDODSSOLFDWLRQVIRUYDULRXVW\SHVRIODVHUV>±@

Overview of the Present State and Development of CVL

17

The Department of Laser Equipment under the scientific guidance RI$**ULJRU¶\DQWVXVHGJDVGLVFKDUJH&2 2Ȝ ȝP VROLG VWDWH 1G@$VSHFLDOSODFHLVRFFXSLHG by the technology of applying images in the volume of transparent media with the help of pulsed laser radiation of the CVL. This technology is unique, because during processing laser radiation is focused into the volume of the material (in glass or quartz), FDXVLQJ LQWHUQDO PLFURIUDFWXUHV > ±@ 0RYLQJ WKH IRFXVHG UDGLDWLRQ VSRW DORQJ WKH YHUWLFDO = D[LV DQG D WUDQVSDUHQW REMHFW LQ WKH SHUSHQGLFXODU SODQH DORQJ WKH WZR ;@ 7KH XVXDOVHOIKHDWLQJSXOVHG&9/ZDVUHSRUWHGLQLQWKHZRUNVRI 7: .DUUDV DQG FRZRUNHUV > @ 2QH RI WKH FUHDWHG &9/V with a diameter and length of the discharge channel of the AE of  PP DQG PPJHQHUDWHGUDGLDWLRQ ZLWKDQDYHUDJH SRZHU RI : ZLWK D 35) RI  N+] ,QLQWKHLawrence Livermore National Laboratory (LLNL) began the program AVLIS on laser isotope separation (LIS) of uranium by the method of selective photoionization in atomic vapour. The purpose of the AVLIS program is to provide an economically advantageous process of large-scale uranium enrichment with the 235 U isotope for the purpose of using it as fuel for nuclear reactors. To perform the three-step selective photoionization in the isolation of the 235U isotope, a wavelength-tunable dye laser with pumping by CVL radiation was chosen because in combination these lasers KDYH SRWHQWLDOO\ KLJK WRWDO SRZHU DQG HIILFLHQF\ >@ +LVWRULFDOO\ the AVLIS program has served as a stimulus for the development of KLJKSRZHU&9/6VZRUNLQJRQDQHIIHFWLYHRSWLFDOPDVWHURVFLOODWRU± SRZHU DPSOLILHU VFKHPH$OUHDG\ LQ  LQ WKH //1/ RQ D 9HQXV installation for the dye laser pumping used a laser system of eight VHOIKHDWLQJ&9/6VZLWKDQDYHUDJHRXWSXWSRZHURI:GLDPHWHU RIDGLVFKDUJHWXEHRIPP LQIURP&9/6VZLWKDWRWDO RXWSXW SRZHU RI  : LQ  ± IURP  &9/6V ZLWK D SRZHU XS WR  : $QG LQ  D VHSDUDWH ODVHU $( ZLWK D GLVFKDUJH WXEH GLDPHWHU RI  PP XVHG DV D SRZHU DPSOLILHU LQ DQ &9/6 JHQHUDWHG D SRZHU RI  : ZLWK D  N+] 35) 'XH WR WKH XVH RI several components of magnetic compression of current pulses in the modulator of the power supply, the power of the radiation from LQGLYLGXDO DPSOLILHUV ZDV UDLVHG IURP  WR  : >@ $W WKH same time there appeared dye lasers tunable along the length with D WRWDO RXWSXW SRZHU RI ± : DQG D OLQH ZLGWK RI “ 0+] ,Q  DQ &9/6 IURP  FLUFXLWV ZLWK D UDGLDWLRQ SRZHU RI  N: ZDV FRQVWUXFWHG LQ  ± IURP  FLUFXLWV ZLWK D SRZHU RI ± N:(DFKFLUFXLWFRQVLVWHGRIRQHPDVWHURVFLOODWRUDQGWKUHHSRZHU

Overview of the Present State and Development of CVL

19

amplifiers; the power take-off from one power amplifier reached ±:7KH XVH RI D QHZ JHQHUDWLRQ RI WKH SRZHU DPSOLILHU LQ WKH&9/PDGHLWSRVVLEOHWRREWDLQDSRZHURIN:>@,QWKLV case, the removal of the radiation power from a separate amplifier ZDVPRUHWKDQ:DWDQHIILFLHQF\RIa7KHV\VWHPFRQVLVWLQJ RI G\H ODVHUV RSHUDWLQJ DFFRUGLQJ WR WKH PDVWHU RVFLOODWRU±SRZHU DPSOLILHU VFKHPH JHQHUDWHG UDGLDWLRQ SRZHU DERYH  N:   ,Q ± QHZ JHQHUDWLRQ HTXLSPHQW ZDV FUHDWHG DQG GHPRQVWUDWLRQ FRPSOH[ WHVWV ZHUH FDUULHG RXW LQFOXGLQJ SRZHUIXO laser systems and separators of industrial scale, allowing to ensure the required productivity of the uranium enrichment process and WKH QHFHVVDU\ SURGXFWLRQ YROXPHV 3URGXFWLRQ FDSDFLW\ FDQ SURYLGH hundreds of kilograms of the required isotope. The CVLS developed KHUH ZLWK WKH WRWDO DYHUDJH UDGLDWLRQ SRZHU ZDV EURXJKW WR  N: DQG D FRPSOH[ RI G\H ODVHU WXQDEOH DORQJ WKH ZDYHOHQJWKV XS WR  N: > @ 3URJUHVV LQ WKH GHYHORSPHQW RI VHOHFWLYH ODVHU WHFKQRORJ\ DOORZHG WKH 8QLWHG 6WDWHV WR EHJLQ LQ WKH HDUO\ V the work on obtaining isotopically enriched plutonium for military SXUSRVHV,QWKH86,VRWRSH(QULFKPHQW&RUSRUDWLRQVXEPLWWHG a plan for the creation of an AVLIS installation of a commercial OHYHOHDUO\ ZLWKIXOOSURGXFWLRQFDSDFLW\LQ7KHDYHUDJH radiation power of the CVL in the AVLIS system of the optical plant ZLOO EH KXQGUHGV DQG WKH G\H ODVHUV ± WHQV RI NLORZDWWV > @ According to some information, it became known that the project of laser enrichment of uranium in the LLNL was first frozen, and WKHQ UROOHG XS$QG WKLV LV H[SODLQHG E\ WKH IDFW WKDW LQ FRQQHFWLRQ with disarmament processes in the world, enough uranium has been DFFXPXODWHG +RZHYHU LW LV DOUHDG\ NQRZQ WRGD\ WKDW LQ  research on the laser separation of uranium was continued by the 86 XUDQLXP FRPSDQ\ 86(& DQG$XVWUDOLDQ 6LOH[ 6\VWHPV /WG 7R date, all major problems in uranium enrichment technology have EHHQ RYHUFRPH DQG LQIRUPDWLRQ KDV DSSHDUHG WKDW *OREDO /DVHU Enrichment was planning to launch a pilot plant for laser enrichment RIXUDQLXPLQ,QFDVHRIFRQGXFWLQJDQGVXFFHVVIXOH[SHULPHQWV on obtaining commercially competitive technology of enrichment of fuel uranium, in relation to traditional technologies, it is planned to FUHDWHDQLQGXVWULDOSODQWZLWKFRPPLVVLRQLQJLQZLWKDGHVLJQ FDSDFLW\RI±PLOOLRQXQLWVRIVHSDUDWLRQZRUNXQLWV(33 >@ 7KHPDLQSURPLVLQJDUHDVIRUWKHXVHRILVRWRSHVH[FHSWXUDQLXP  obtained by the selective AVLIS technology, are nuclear power engineering, medicine, biology, and scientific and practical research.

20

Laser Precision Microprocessing of Materials

The qualitative development of laser technology over the past decade allows us to put on a new generation of productive industrial isotope separation plants. In connection with the large reserve of already enriched uranium, pulsed CVLs began to be applied in other fields of science and technology. These include the current laser micromachining of materials, medicine, spectral studies on the analysis of the composition of substances, increasing the brightness of the image, speed photography, etc. Therefore, some US firms have begun to GHYHORS ORZSRZHU FRPPHUFLDO DLUFRROHG &9/V )RU H[DPSOH WKH FRPSDQ\/DVHU1RZDGYHUWLVHV&9/PRGHOV&9/:DQG&9/: 7KHDYHUDJHUDGLDWLRQSRZHURIWKHPRGHO&9/:ZLWKDGLDPHWHU RI WKH GLVFKDUJH FKDQQHO RI  PP LV DERXW  : &9/: ZLWK D FKDQQHO GLDPHWHU RI  PP KDV D SRZHU RI  : ZLWK D 35) RI  N+] 7KH PLQLPXP OLIHWLPH RI VROGHUHG $( &9/: LV  K &9/:LVK$JURXSRIH[SHULHQFHGVFLHQWLVWVIURPWKH86$ DQG.RUHDIURP%,6210(',.$/KDVGHYHORSHGDQHZJHQHUDWLRQ medical device Cooper Bromide for innovative technologies in dermatology and cosmetology. The basis of the medical device is a pulsed low-power laser with sealed AE on copper bromide. The firm ZDVHVWDEOLVKHGLQLQWKH86$&DOLIRUQLD7KHGHYLFH&RRSHU Bromide effectively treats vascular and pigmentary pathologies and other skin diseases. Vascular pathologies include teleantiectasias, µZLQH VSRWV¶ KHPDQJLRPDV VHQLOH DQJLRPD SLJPHQWRVD ± IUHFNOHV OHQWLJRPHODVPDDQGRWKHUGLVHDVHV±ZDUWVDFQHVFDUVZULQNOHVDQG senile skin defects. Another well-known company in the US for the GHYHORSPHQW DQG SURGXFWLRQ RI FRPPHUFLDO /02V IRU DSSOLFDWLRQV in science, technology and medicine is Metalaser Technologies Inc. The development of CVL in France, Japan, Britain, China, Israel, India and other countries.3URJUDPVVLPLODUWRWKH86$9/,6 programs, with the use of CVL and dye lasers in multicomponent PDVWHU RVFLOODWRU±SRZHU DPSOLILHU V\VWHPV 02±3$ V\VWHP  KDYH also been developed in other countries. These include, first of all, )UDQFH -DSDQ %ULWDLQ &KLQD ,VUDHO ,QGLD %UD]LO .RUHD In France, the development of the $9/,6SURJUDPEHJDQLQ DVSDUWRIWKHGHYHORSPHQWRIWKHQH[WJHQHUDWLRQLVRWRSHHQULFKPHQW technology. CVL is developed by the Ministry of Atomic Energy and &,/$6FRPSDQ\>@,Q±\HDUVWKHSRZHUDPSOLILHUV ZLWK DQ DYHUDJH RXWSXW SRZHU RI  : KDYH DOUHDG\ EHHQ XVHG DQGLQ&9/6VZLWKWKUHH3$VZLWKDWRWDORXWSXWSRZHURI : ZHUH GHPRQVWUDWHG 7KH 02 KDG D SRZHU RI  : ZLWK D 35)

Overview of the Present State and Development of CVL

21

RI ± N+] ,Q  DORQJ ZLWK D WK\UDWURQ SRZHU VRXUFH VROLG state sources with transistor switches, in particular, for CVL with a SRZHU RI  : EHJDQ WR EH GHYHORSHG$QG LQ WKH VDPH \HDU WKH WRWDORXWSXWFDSDFLW\RIWKH&9/LQWKHV\VWHPZLWKVL[FLUFXLWVZDV  N: ,Q  WKH $67(5 LQVWDOODWLRQ ZDV GHPRQVWUDWHG ZKLFK obviously became the basis for future industrial developments for $9/,6WHFKQRORJ\>@)RUWRGD\WKHUHLVLQIRUPDWLRQWKDWLQWKH )UHQFK ODVHU V\VWHPV IRU VHSDUDWLQJ LVRWRSHV KLJKSRZHU 1G @ +LWDFKL 7RVKLED 0LWVXELVKL .DQVDL HWFZHUHLQYROYHGLQGHYHORSPHQWRI&9/,QIRULQGLYLGXDO &9/V WKH RXWSXW DYHUDJH SRZHU RI WKH UDGLDWLRQ ZDV  : DQG ZDV GHPRQVWUDWHG E\ WKH &9/6 RSHUDWLQJ DFFRUGLQJ WR WKH 02±3$ VFKHPHSRZHU:,QWKH0LWVXELVKLFRPSDQ\ODXQFKHGWKH &9/ ZLWK D SRZHU RI :ZKHQRSHUDWLQJLQWKHJHQHUDWRUPRGH DQG  ZDWWV LQ WKH 3$ PRGH > @ %\  WKH &9/ ZLWK D GLDPHWHU RI WKH GLVFKDUJH FKDQQHO RI WKH $( RI  PP JHQHUDWHG  : >@ 7KH WDVN RI LQFUHDVLQJ WKH UDGLDWLRQ SRZHU IRU WKH /$6(5-SURJUDPZDVVROYHGLQE\7RVKLEDWKHRXWSXWRIRQH &9/UHDFKHG:LQWKHJHQHUDWRUPRGHDQG:LQWKHSRZHU DPSOLILHUPRGH>@7KHGLDPHWHUDQGOHQJWKRIWKHGLVFKDUJHWXEH RIWKH$(ZHUHPPDQGPPUHVSHFWLYHO\$FFRUGLQJWRWKH /$6(5-SURJUDPLWLVSODQQHGWRGHPRQVWUDWHDQLQGXVWULDOXUDQLXP HQULFKPHQW SODQW  8 7KHUHIRUH LQ ± UHVHDUFK DQG development of a new technology for separation of isotopes, different from traditional classical methods (centrifugation and gas diffusion separation), received rapid development, and investments amounted to hundreds of millions of dollars. Ideally, AVLIS-technology of uranium enrichment should become a technology of the 21st century, LH LW LV FRPSDFW DXWRPDWHG DQG PD[LPDOO\ VDIH >@ 6SHFLDOLVWVIURP7RVKLED>@DQG>@SXEOLVKHGLQ independently of one another the data on the use of baffles in largeGLDPHWHU ± PP $(V RI WKH &9/ GLVFKDUJH WXEHV DOORZLQJ WR reduce the radial gradient of temperature and concentration atoms of copper and, accordingly, to increase the specific absorption of

22

Laser Precision Microprocessing of Materials

radiation power from the active medium. In LLNL a CVL with a GLDPHWHU RI D GLVFKDUJH WXEH RI  PP $( LQ 80 PRGH ZLWKRXW partitions generated radiation with an output average power of 255 : ZLWK DQ HIILFLHQF\ RI  ZLWK SDUWLWLRQV ±  : ZLWK DQ HIILFLHQF\ RI  >@ ,Q2[IRUG/DVHUV*UHDW%ULWDLQ FUHDWHGDVPDOOLQVWDOODWLRQ based on the CVL and LRK to evaluate the AVLIS program, but in  LW ZDV GHFRPPLVVLRQHG >@ ,Q WKH VDPH \HDU WKH FRPSDQ\ produced the first commercial CVL with an average output power RI  ZDWWV ,W KDV GHYHORSHG DQG SURGXFHV &9/ PRGHOV$&/ $&/$&/$&/,Q2[IRUG/DVHUVFUHDWHGD± : &9/ ZLWK DLU FRROLQJ DQG VLQJOHSKDVH SRZHU VXSSO\ IURP WKH PDLQVDQGZDWWVDQGZDWWVDOVRZLWKDLUFRROLQJEXWWKUHH SKDVHPDLQVSRZHU$QRWKHU(QJOLVKFRPSDQ\((9 LQEHJDQ to put on the CVL market with sealed AEs. By the firm “CI Laser” in PRGHOVRI&9/ZLWKDSRZHUIURP±:WR:DVZHOODV /3%D/33EDQG/3$XZHUHRIIHUHG7KLVFRPSDQ\VSHFLDOL]HVLQWKH production of MetVL for forensic science, high-speed photography, on-board systems. Today, 2[IRUG /DVHUV DGYHUWLVHV WKH QHZHVW &9/ PRGHOV /6  /6 DQG /6 GHVLJQHG IRU KLJKVSHHG WUDQVPLVVLRQ RI LPDJHVDQGYLVXDOL]DWLRQRIDLUERUQHGXVWDQGVFLHQWLILFUHVHDUFK>@ The main parameters of the CVL are the following: the radiation ZDYHOHQJWK LV  QP WKH &3, LV ± N+] WKH SXOVH GXUDWLRQ LVQVWKHDYHUDJHUDGLDWLRQSRZHULV±:GHSHQGLQJRQWKH PRGHO WKHMLWWHULVQRPRUHWKDQ±QVDQGWKHUHOLDEOHH[SORLWDWLRQ $VDQRSWLRQIRUWKHODVHU±fiber delivery of radiation. An important area of application of pulsed CVL is precision microprocessing of materials. To solve the tasks on microprocessing, a laser WHFKQRORJLFDOLQVWDOODWLRQRIWKH03;PRGHOEDVHGRQWKH/630 RSHUDWLQJ DFFRUGLQJ WR WKH 02±3$ VFKHPH >@ ZDV FUHDWHG7KH device provides the possibility of converting the visible yellow-green UDGLDWLRQ RI /60: E\ PHDQV RI QRQOLQHDU FU\VWDOV WR XOWUDYLROHW ZLWK ZDYHOHQJWKV RI  DQG  QP ZKLFK H[SDQGV WKH ILHOG RI LWV SUDFWLFDO DSSOLFDWLRQ 7KH PDLQ SDUDPHWHUV RI WKH /030 RI WKH 03; GHYLFH DUH UDGLDWLRQ ZDYHOHQJWKV RI  DQG  QP 35) RI ± N+] D SXOVH GXUDWLRQ RI  QV EHDP GLYHUJHQFH RI  PUDG DQ DYHUDJH SRZHU RI  : ZLWK D  N+] 3,& DQG D SRZHU FRQVXPSWLRQ RI DERXW  N: 7KH ZRUNLQJ ILHOG RI WKH horizontal coordinate table XY, where the object to be processed LV LQVWDOOHG KDV D VWURNH VL]H RI  î  PP DQG SRVLWLRQLQJ

Overview of the Present State and Development of CVL

23

DFFXUDF\ DORQJ WKH  ȝP D[HV WKH OHQJWK RI WKH YHUWLFDO WDEOH = WUDYHO ZLWK D IRFXVLQJ OHQV RI  PP DQG DQ DFFXUDF\ RI  ȝP A technological plant with such characteristics allows producing HIILFLHQWSURFHVVLQJRIPHWDOOLFPDWHULDOVZLWKDWKLFNQHVVRI± PPZLWKDFXWWLQJZLGWKRIPRUHWKDQȝPDQGIODVKLQJKROHVZLWK D GLDPHWHU RI ± ȝP 7KH PDLQ DQG VLJQLILFDQW GLVDGYDQWDJH RI the 03; LQVWDOODWLRQ LV WKDW WKH $(V LQ &9/6 RSHUDWH LQ WKH neon buffer gas pumping mode, that is, the technology of their manufacture does not allow operating in the sealed mode. It is known that the operating mode of operation reduces the service life of the laser and worsens the stability of the output radiation SDUDPHWHUV ,Q D QXPEHU RI H[SHULPHQWDO SURFHVVLQJ RSHUDWLRQV 2[IRUG/DVHUVHPSOR\HHVGHPRQVWUDWHGXQLTXHSRVVLELOLWLHVRIXVLQJ pulsed nanosecond radiation from CVL for precision microprocessing RI YDULRXV PDWHULDOV > @ SILVA is the European program on AVLIS technology. The most important components for laser isotope separation equipment were GHYHORSHGLQ)UDQFH-LODV$OFDWHO DQGLQ(QJODQGE\2[IRUG/DVHUV >@ *UHDW LQWHUHVW LQ WKH SUDFWLFDO GHYHORSPHQW RI ODVHU LVRWRSH separation is shown by China, Israel, India, Brazil, Korea and other countries. A partial review of these studies is presented in [23, ref.. @,Q&KLQDIRUWKLVSXUSRVHWKHILUVWSRZHUIXO&9/9: ZDV created at the Institute of Electronics of the Chinese Academy of 6FLHQFHV %HLMLQJ   >@ ,Q ,VUDHO ZRUNV RQ $9/,6 XVLQJ CVL are being conducted at the Nuclear Research Center in Negev. ,Q  LW ZDV UHSRUWHG RQ WKH &9/ ZLWK D GLVFKDUJH WXEH ZLWK D GLDPHWHU RI  PP RSHUDWLQJ DW  N+] )3, >@ ,Q WKH JHQHUDWRU PRGHWKHRXWSXWSRZHURIWKH&9/UDGLDWLRQZDV:LQWKH80 PRGH  : 7KLV &9/ ZDV XVHG WR SURFHVV PDWHULDOV LWV IRFXVHG output beam produced holes in a steel sheet 1 mm thick. Then CVL ZDV GHYHORSHG ZLWK D SRZHU  “   : DQG  “   : ZLWK D GLDPHWHU RI WKH GLVFKDUJH WXEH LI WKH $(  “   PP DQG  “   PP UHVSHFWLYHO\ DW 35)  “   N+] )RU WKH ILQJHUSULQW LGHQWLILFDWLRQ V\VWHP D VROGHUHG /03 ZLWK D SRZHU RI  : ZDV FRQVWUXFWHGJHQHUDWLQJDUDGLDWLRQEHDPZLWKDGLDPHWHURIPP (YHU\  KRXUV RI RSHUDWLRQ WKH$( LV UHSODFHG ZLWK D QHZ RQH This CVL employs a solid-state switch with a service life of more WKDQ   K7KHAVLIS program with CVL is also being carried RXW LQ ,QGLD ± DW WKH &HQWHU IRU$GYDQFHG 7HFKQRORJ\ ,QGRUH  DQG the Bombay Atomic Research Center.

24

Laser Precision Microprocessing of Materials

3RZHUIXO &9/V XVHG LQ $9/,6 SURJUDPV XVXDOO\ ZRUN LQ WKH continuous mode of pumping neon buffer gas through the AE (at D UDWH RI ± OLWHUVKRXU  DQG DIWHU ± KRXUV RI ZRUN D QHZ portion of the active substance (copper) needs to be laid. Bleeding is necessary to remove impurity gases that are continuously generated from materials of AE elements due to high operating temperature aƒ&  %DVHGRQWKHLQIRUPDWLRQPDWHULDOVDYDLODEOHWRGD\PRUHWKDQ countries are in the process of researching and obtaining weights of different isotopes by laser isotope separation in Argentina, Australia, %UD]LO %ULWDLQ &KLQD )UDQFH *HUPDQ\ ,QGLD ,UDT ,VUDHO -DSDQ 7KH 1HWKHUODQGV 3DNLVWDQ 5RPDQLD 5XVVLD 6RXWK .RUHD 6RXWK Africa, Spain, Sweden, Switzerland, USA, Yugoslavia. The following isotopes are of the greatest interest: 235U, Ba, 176Yb, 43Ca, 48Ca,  Zn, Nd, 25Mg, Tl, 87Rb, 155Cd, 157Cd, etc. CVL of the German firm Atzevus. Atzevus has advertised copper vapor lasers CVL 175 plus, CVL 275 plus and CVL 375 plus with an DYHUDJHUDGLDWLRQSRZHURIDQGZDWWVUHVSHFWLYHO\ZLWK D &35 RI  N+]  HIILFLHQF\  DQG   DQG :$W WKH &3, RI  N+]  HIILFLHQF\  7KHVH PRGHOV ZRUN DFFRUGLQJ WR WKH PDVWHU RVFLOODWRU±SRZHU DPSOLILHU 02±3$  VFKHPH 7KH GLDPHWHU RI WKH GLVFKDUJH FKDQQHO RI WKH$( 02 ±  PP$( 3$ ±  PP ,Q &9/  SOXV RQH 3$ LV XVHG LQ &9/  SOXV ± WZR 3$V LQ &9/  SOXV ± WKUHH 3$V 7KHVH &9/V DUH LQWHQGHG IRU the acquisition of process equipment for high-performance precision SURFHVVLQJZLWKPLFURQDFFXUDF\RIVKHHWPHWDOPDWHULDOVXSWR± mm thick. The most powerful CVL 375 plus is used for cutting and drilling of titanium parts. Today we do not know any new GDWD RQ WKH GHYHORSPHQW RI WKLV FRPSDQ\7KH ZHOONQRZQ *HUPDQ companies Trumpf and Rofin Sinar Laser develop and produce mainly technological equipment based on their own production lasers and production of other enterprises for productive and high-quality FXWWLQJZHOGLQJVXUIDFLQJDQGPLFURSURFHVVLQJ>@7KHDSSOLHG technological lasers include both continuous and pulsed &2 2 lasers, VROLGVWDWH ODVHUV RQ 1G @ In order to increase the efficiency (capacity and efficiency) and UHOLDELOLW\ RI WKH &9/ WKH UHVHDUFK SURMHFWV .ULROLW ±  DQG .ULROLW ±  ZHUH FDUULHG RXW /LWHUDWXUH GDWD ZHUH V\VWHPDWL]HG DQG H[SHULPHQWDO VWXGLHV RI WKH WKHUPRSK\VLFDO DQG vacuum properties and chemical composition of various powder and fibrous heat insulators were carried out. The coefficients of

28

Laser Precision Microprocessing of Materials

heat conductivity of heat insulators as a function of the pressure of the buffer gas, the temperature and density of the heat insulator, the composition of the gases released during the training of the AE were studied. It has been shown that for a combination of positive properties, the most suitable materials for a thermal insulator with an operating temperature of Toper  @ D &9/ ZDV VWXGLHG DW KLJK SUHVVXUHV RI WKH QHRQ buffer gas, which is important for increasing the life of the AE. In the Kriostat project, the lifetime of the sealed self-heating AE was DERXW  KRXUV DW D EXIIHU JDV QHRQ  SUHVVXUH RI  PP +J  N+] DQG WKH SRZHU FRQVXPHG IURP WKH UHFWLILHU RI WKH SRZHU VRXUFH ZDV ± N: >@$IWHU  KRXUV RI RSHUDWLQJ WLPH WKH UDGLDWLRQ SRZHU ZDV UHGXFHG E\ KDOI IURP  WR  :  $W WKH same time, the practical efficiency was very low and amounted to ± WKDW LV DW WKH OHYHO RI WKH HIILFLHQF\ RI DQ DUJRQ ODVHU The period 1980–1989. This period begins with the research work .ULVWDOO ±  LQ ZKLFK DV D UHVXOW RI H[WHQVLYH UHVHDUFK WKUHH W\SHV RI VHDOHG VHOIKHDWLQJ $(V RQ FRSSHU YDSRUV ± .XORQ Kvant and Kristall with an average radiation power of 1 up to 15 watts. The minimum (guaranteed) operating time of the AE was LQFUHDVHG E\ ± WLPHV XS WR ± K  WKH DYDLODELOLW\ DQG power consumption decreased significantly. Research work Kristall was the basis for the R & D Kvant, Kristall-1 and Kulon, within the framework of which industrial sealed-off AEs of the new generation ZLWKDFHUPHWVKHOOZHUHDOUHDG\GHYHORSHG:KHQGHYHORSLQJ$(DQG creating radiators, lasers, technological and medical devices based on them, the main attention was paid to increasing the efficiency, power, specific characteristics, the quality of radiation, improving the operational parameters and their reproducibility in the process of long operating time. ,Q WKH .YDQW SURMHFW ±  DQ$( ZDV GHYHORSHG ZLWK D PLQLPXP RSHUDWLQJ WLPH RI DW OHDVW  K D UHDGLQHVV WLPH RI QRW

30

Laser Precision Microprocessing of Materials

PRUH WKDQ  PLQ DQG D JDLQ RI DW OHDVW  G% IRU XVH DV DQ LPDJH EULJKWQHVVDPSOLILHULQSURMHFWLRQPLFURVFRSHVRIWKH&9/W\SH DQG WHFKQRORJLFDO LQVWDOODWLRQV VXFK DV /XFK 7KH $( .YDQW LQ accordance with the technical specifications (TU) has the symbol 8/7KH UDWLR RI WKH OHQJWK RI WKH GLVFKDUJH FKDQQHO  PP  WRWKHGLDPHWHURIWKHDSHUWXUHRIWKH$(PP ZKLFKGHWHUPLQHV WKH ILHOG RI YLHZ RI WKH PLFURVFRSH LV   7KH UDGLDWLRQ SRZHU RI WKH GHYLFH LQ WKH JHQHUDWRU PRGH LV ±: ,QWKH.ULVWDOOSURMHFW± WKHILUVWGRPHVWLFLQGXVWULDO sealed AE was developed with a relatively high average radiation SRZHU ±:  ZLWK D 35) RI ± N+] D UHDGLQHVV WLPH RI QRW PRUH WKDQ  PLQ D PLQLPXP ZRUNLQJ WLPH RI DW OHDVW  K IRU use as part of a progressive process equipment for the manufacture of electronic products. The Kristall-1 AE in accordance with the WHFKQLFDO VSHFLILFDWLRQ KDV WKH V\PERO */$W WKH VDPH WLPHD VPDOOVL]HG .XORQ$( */ DFFRUGLQJ WR 78  ZDV FUHDWHG ZLWK D UDGLDWLRQ SRZHU RI ±: ZLWK D 35) RI ± N+] %DVHG RQ WZR $(V */V LQ WKH SHULRG IURP  WR  The first domestic CVL .DUHOL\D /*,  ZLWK KLJK HQHUJ\ characteristics and high radiation quality, operating according to the 023$ VFKHPH ZDV GHYHORSHG DQG LQYHVWLJDWHG 3XPSLQJ RI WKH AE is carried out from a two-channel synchronized thyratron or tube power source. The average radiation power of a two-channel CVL is DW OHDVW  : SXOVHG SRZHU RI  N:  LW KDV D GLYHUJHQFH RI WKH RXWSXW EHDP IURP VHYHUDO PLOOLUDGLDQV WR ± PUDG GLIIUDFWLRQ OLPLW DWD35)RI±N+]:LWKWKLVTXDOLW\RISXOVHGUDGLDWLRQWKH ILUVW H[SHULPHQWDO VWXGLHV ZHUH FDUULHG RXW LQ  RI WKH SURFHVVHV of cutting and drilling with a laser beam of various materials with D WKLFNQHVV RI ± PP &X$O 0R7D: '7 &U1L7L 89. IRLOHG WH[WROLWH SOH[LJODV DQG HWF  The two-channel CVL Kareliya became the basis for creating a laboratory semi-automated laser technological installation (LTI) .DUDYHOOD ±  GHVLJQHG IRU SUHFLVLRQ SURFHVVLQJ RI materials used in the manufacture of electronic products. The LTI demonstrated the possibility of precision cutting and drilling of a large group of metals, semiconductor and dielectric materials, many of which were not included in the sphere of laser microprocessing until now. It is shown that Karavella LTI allows to shorten the terms of manufacturing small and medium-sized batches of electronic products by an order of magnitude in comparison with traditional methods of processing, including electric sparking.

Overview of the Present State and Development of CVL

31

$W WKH VDPH WLPH   DQ H[SHULPHQWDO ODVHU PHGLFDO GHYLFH Yantar’-F with the CVL Kareliya with an average radiation power RI DW OHDVW  : ZDV FUHDWHG IRU ORFDOL]HG WKHUPDO HIIHFWV RQ pathological foci (coagulation, therapy, surgery). The fiber lightguide, WUDQVPLWWLQJ WR WKH REMHFW SXOVHG UDGLDWLRQ RI &9/ ZDV D IOH[LEOH TXDUW]PRQRILODPHQW±PPLQGLDPHWHUZLWKDQRXWHUSURWHFWLYH shell. The main advantage of a quartz fiber is its high radial strength XS WR  ± 11 :FP 2). Therefore, in a fiber with small diameters it is possible to transmit ‘large’ average powers of pulsed radiation (units and tens of watts). 2QH*/$(ZDVXVHGDVDEDVLVLQWRGHYHORSWKH.OHQ UDGLDWRU,/*,DFFRUGLQJWR78 DQGEDVHGRQLWLQD&9/ .XUV/*, ZLWKWKHXSJUDGHGWK\UDWURQSRZHUVRXUFH,37KH WRWDO DYHUDJH RXWSXW SRZHU RI WKH /*, ODVHU LV ± : ZLWK D  N+] 35) DQG WKH SRZHU FRQVXPHG IURP WKH ,3 UHFWLILHU RI DSSUR[LPDWHO\N:WKHJXDUDQWHHGRSHUDWLQJWLPHWRIDLOXUHZDV K7KHODVHUZDVGHVLJQHGIRUSXPSLQJZDYHOHQJWKWXQDEOHG\H ODVHUV ± ȝP  IRU PHGLFDO DQG WHFKQRORJLFDO LQVWDOODWLRQV and scientific research. 'XULQJWKLVSHULRGDODUJHDPRXQWRIH[SHULPHQWDODQGWKHRUHWLFDO work was carried out to increase the power and efficiency of a copper vapour laser, to study the structure and improve the quality RILWVRXWSXWUDGLDWLRQ>±@,WLVHVWDEOLVKHGWKDWWKHVWUXFWXUH of radiation with an optical resonator is multicellular (usually three to five beams are observed). Each radiation beam has its spatial, temporal and energy characteristics. The use of an unstable resonator of a telescopic type with an magnification factor M  ±OHDGVWRWKHIRUPDWLRQRIUDGLDWLRQEHDPVZLWKDGLYHUJHQFH close to diffraction. In the mode of operation with a single mirror, WKH UDGLDWLRQ VWUXFWXUH LV RI WKH WZREHDP W\SH :LWK RQH FRQYH[ mirror the radius of curvature of which is two orders of magnitude smaller than the length of the AE, a beam with a divergence close to the diffraction and high stability of the radiation characteristics LV IRUPHG > @ 7KH VWUXFWXUH RI WKH RXWSXW UDGLDWLRQ DQG LWV FKDUDFWHULVWLFV LQ WKH &9/6 RSHUDWLQJ DFFRUGLQJ WR WKH 02±3$ VFKHPH >±@ ZDV VWXGLHG The period 1990-2002. This period of development of sealed-off self-heating CVLs is characterized by the search for and creation of new design and technological solutions, effective electrical pumping schemes to increase the guaranteed (minimum) AE production up WR  K DQG DERYH DYHUDJH UDGLDWLRQ SRZHU WR ± : ZLWK D

32

Laser Precision Microprocessing of Materials

SUDFWLFDOHIILFLHQF\RIDWOHDVWSXOVHGUDGLDWLRQSRZHUXSWR±  N: HQHUJ\ LQ SXOVH XS WR ± P- 7KH VSDWLDO DQG WHPSRUDO characteristics of the output radiation of CVL with such power levels for different optical systems both in the generator mode and in the power amplifier mode are studied. The development of powerful and reliable CVLs with high radiation quality was stimulated by the need to create domestic laser process units for the separation of isotopes for the needs of nuclear power engineering, installations for highperformance precision microprocessing of materials of electronic HTXLSPHQW DQG PRGHUQ PHGLFDO IDFLOLWLHV >  ±@ ,QWKH.XEDQ¶UHVHDUFKSURMHFW± DQH[SHULPHQWDO&9/ ZLWK D V\QFKURQL]HG WKUHHFKDQQHO WK\UDWURQ 36 DQG D PRGHUQL]HG radiator .DUHOL\D RSHUDWLQJ DFFRUGLQJ WR WKH 02±3$ VFKHPH ZLWK DQ DYHUDJH UDGLDWLRQ SRZHU RI ± : D SXOVHG SRZHU RI  N: SXOVH HQHUJ\  P- DQG EHDP GLYHUJHQFH FORVH WR GLIIUDFWLRQ ±PUDG DWN+]35)ZDVFRQVWUXFWHG7KHPDVWHURVFLOODWRU ZDVWKH.XORQ$(*/ ZLWKDSRZHURI±:GLDPHWHURIWKH GLVFKDUJH FKDQQHO  PP  WKH SRZHU DPSOLILHU ± WZR .ULVWDOO' $(V SRZHU ±: FKDQQHO GLDPHWHU  PP   The Kurs CVL was used in the development of the first relatively powerful laser medical devices of the type Yantar’-2F DQG ±@ ,Q WKH .DUDYHOOD SURMHFW LQ  WKH ILUVW GRPHVWLF LQGXVWULDO ALTI Karavella-1 was developed on the basis of two-channel CVL

34

Laser Precision Microprocessing of Materials

DQGDWKUHHFRRUGLQDWHWDEOHZLWK3&FRQWUROLQWHQGHGIRUSURGXFWLYH DQGKLJKTXDOLW\SUHFLVLRQPLFURSURFHVVLQJRIPHWDOPDWHULDOV±  PP WKLFN IRU HOHFWURQLF HTXLSPHQW FRPSRQHQWV ((&  7KH &9/ FRQVLVWV RI D UDGLDWRU ZLWK WZR VHDOHG$(V */' IURP WKH .XORQ VHULHV ZLWK DQ DYHUDJH UDGLDWLRQ SRZHU RI  : SURGXFHG by the ,VWRN FRPSDQ\  RSHUDWLQJ XQGHU WKH 02±3$ VFKHPH DQG a high-voltage two-channel transient power source with a power FRQVXPSWLRQ IURP D WKUHHSKDVH  N: QHWZRUN DW 35) RI ± kHz and accuracy of channel synchronization ±2 ns (development RI &KLVW\H WHNKQRORJLL ,]KHYVN  7KH WKUHHD[LV WDEOH LV FUHDWHG RQ the basis of linear synchronous motors and includes a horizontal XY WDEOH ZLWK D ZRUNLQJ ILHOG RI  î  PP ZKHUH WKH PDWHULDO WR be processed is mounted and a vertical table Z with a focusing lens DQGDZRUNLQJVWURNHRIPPZLWKDFFXUDF\RISRVLWLRQLQJIRUHDFK D[LVQRWZRUVHWKDQ“—P3UHWVL]LRQQ\HWHNKQRORJLL0RVFRZ 7KH operating modes and processing of ALTI are automated and controlled from the computer through the control unit in accordance with the FUHDWHGEDVLFVRIWZDUH3URJUDPVIRUGUDZLQJVRIPDQXIDFWXUHGSDUWV are compiled in AutoCad in DXF format. The ALTI Karavella-1 in WKHSHULRG±ZLWKLQWKHIUDPHZRUNRIWKH.XUVRUSURMHFWZDV XVHGIRUDODUJHYROXPHRIH[SHULPHQWDOVWXGLHVRQPLFURSURFHVVLQJ (cutting and drilling) of various thin-film materials with a thickness RI±PPZLWKDQDYHUDJHUDGLDWLRQSRZHUP ±:DQG a focal length of an achromatic lens F    DQG  PP WKH cutting speed V  ± PPV DQG WKH QXPEHU RI SDVVHV N  ± Based on the results of the research, a computer database has been FUHDWHGLQWKHIRUPRI([FHOVSUHDGVKHHWVDQGWHFKQRORJLHVKDYHEHHQ developed for the precision manufacture of parts from molybdenum, copper, titanium, stainless steel, silicon and artificial polycrystalline GLDPRQG $QQXDOO\ IURP  WR  KXQGUHGV RI WKRXVDQGV RI SDUWVRIDVLPSOHDQGFRPSOH[FRQILJXUDWLRQZHUHPDQXIDFWXUHGDWWKH ,VWRN 5HVHDUFK DQG 3URGXFWLRQ (QWHUSULVH LQ WKH$/7, .DUDYHOOD mainly with two-shift operation, in the development and manufacture of microwave devices, with high processing quality and micron DFFXUDF\ ,Q  ZLWKLQ WKH IUDPHZRUN RI WKH 8GDU /7 SURMHFW using ALTI Karavella-1, the processing technology for a number of critical parts of atomic-beam tubes on cesium vapour was tested. In 7 years of almost continuous operation of ALTI, a number of design flaws were revealed, which reduced its reliability, quality and manageability, which were taken into account in subsequent GHYHORSPHQWV :LWK WKH SXUSRVH RI IXUWKHU KLJKTXDOLW\ RSHUDWLRQ

Overview of the Present State and Development of CVL

35

RI $/7, .DUDYHOOD LQ  WKH ROG WZRFKDQQHO SRZHU VRXUFH of the CVL was replaced with a new one, with high reliability and controllability and optimization of the optical system for the formation of a diffraction beam of radiation was carried out. ,Q  WKH Istok enterprise developed an industrial ALTI Karavella-1M, which differs from the Karavella installation by higher power and radiation quality, reliability and controllability. 7KH3$RIWKHHPLWWHURIWKH&9/XVHDQ$(ZLWKDIROGLQFUHDVH LQWKHSRZHU*/,±: LQ02ZLWKWKH$(*/'±DQ XQVWDEOHRSWLFDOUHVRQDWRUZLWKWZRFRQYH[PLUURUVIRUWKHIRUPDWLRQ of single-beam radiation with diffraction divergence. According to preliminary estimations of the developers of the power source (Chistye tekhnologii), the guaranteed operation of the dual-channel upgraded transistor power source, due to the use of new solutions in the nodes of the high-voltage modulator and their placement in liquid oil with high electrical strength and components with high UHOLDELOLW\ VKRXOG LQFUHDVH DW OHDVW WZR WLPHV ± XS WR ± K Moreover, the new power source should provide not only a packet, as in ALTI Karavella-1, but also a pulse-modulated radiation. The three-coordinate table in this setup is identical to the coordinate table in ALTI Karavella-1. An increase in the mean power of radiation LQ D EHDP RI GLIIUDFWLRQ TXDOLW\ WR ±: LQ$/7, .DUDYHOOD0 allowed to increase not only the productivity and processing quality, EXWDOVRWKHWKLFNQHVVRIWKHSURFHVVHGPDWHULDOV±PHWDOXSWRPP silicon and polycrystalline diamond up to 2 mm. ,Q $/7, .DUDYHOOD ZDV GHYHORSHG DQG SXW LQWR RSHUDWLRQ on the basis of industrial single-channel CVL Kulon-15 with packet DQGSXOVHLPSXOVHPRGXODWLRQDW±N+]35)PDQXIDFWXUHGE\WKH VELIT Company. The most powerful sealed-off AE from the series .XORQ±*/,ZLWKSRZHULQDKLJKTXDOLW\EHDPRI±:LVXVHG in CVL when operating in a mode with a telescopic resonator with M 7KHZRUNLQJILHOGRIWKHKRUL]RQWDOFRRUGLQDWHWDEOH;@7KHTXDOLW\RIWKHKROHLQfiber drilling is close to the quality of conventional mechanical processing methods. Radiation treatment by CVL of ceramics and transparent materials. The rigidity and fragility of ceramics greatly impedes processing by conventional methods. The radiation of CVL can also be used to process ceramics. The CVL like the H[FLPHU ODVHU with relatively short length waves and high peak capacity allows fully remove the ceramics from the processing place without the formation of a glass mass layer (which is observed in the case of @ 7KH GLDPHWHURIWKHVHPLFURKROHVLV±—PWKHGHSWKLVXSWRPP WKHIRUPIDFWRUH[FHHGV>±@6XUIDFHVRIKROHVKDYHJRRG RSWLFDOTXDOLW\7KHGULOOLQJVSHHGLVXVXDOO\DERXWPPVZKLFKLV FORVHWRWKHOHYHOIRUPHWDOV±PPV ,QWKHVKHHWVRITXDUW] JODVV WKH URXQGHG JURRYHV DUH FXW DW D VSHHG RI  PPPLQ 2Q WKH surface of the transparent target there is a clearly defined entrance opening and a long section with a very small taper, the length of ZKLFK LV  WLPHV WKH GLDPHWHU RI WKH LQOHW 7KH KROH LV µEOLQG¶ RU open ending in the top. Drilling is initiated either with the formation of a colour centre, or after surface breakdown at peak power density OHYHOV RI  ā  ± :FP 2. To do this, even an average radiation SRZHURI:LVVXIILFLHQWIRUWKHGLIIUDFWLRQTXDOLW\RIWKHEHDP 7KH GULOOLQJ VSHHG UHDFKHV  ȝP SHU SXOVH After surface breakdown of the target (when an inlet is formed), the laser energy is directed along a smooth hole to the front of the laser drill. The resulting absorbing plasma, associated with the front of the drill, has a bright glow and is clearly visible as the hole deepens. At the end of the pulse, the gas overheating in the hole UHDFKHV D PD[LPXP DIWHU ZKLFK D VWURQJ H[SDQVLRQ EHJLQV KRW steam, forming a luminous torch, is pushed out under the action of D VKRFN ZDYH$W WKH HQHUJ\ RI WKH UDGLDWLRQ SXOVH EHORZ a P- the drilling process of the material ceases. Since ‘pulsed’ holes in transparent materials are very effectively drilled with pulsed radiation from the CVL, this laser is very promising for the application of volumetric markings and images. Radiation of the CVL can also be used for the processing of natural and artificial diamonds. The walls of the hole in the diamonds are obtained clean and high quality (as in other materials) which indicates the direct removal of the atoms from the impact zone. $W UHODWLYHO\ ORZ GHQVLWLHV RI WKH SHDN SRZHU a ā    :FP 2 ) the diamond at first is transformed to graphite (with heating up to

50

Laser Precision Microprocessing of Materials

ƒ& ZKLFKVWUHQJWKHQVDEVRUSWLRQUDGLDWLRQDQGDFFHOHUDWHVWKH UHPRYDO RI PDWHULDO GXH WR R[LGDWLRQ DQG HYDSRUDWLRQ >@ Underwater processing by radiation of CVL7KH\HOORZ±JUHHQ region of the visible spectrum of radiation is well transmitted through quartz lightguides and water, so the CVL can be successfully used LQXQGHUZDWHURSHUDWLRQV>@DVZHOODVLQUHSDLUZRUNDWQXFOHDU facilities and offshore platforms. The CVL with an average output SRZHU RI  : FDQ FXW XQGHU ZDWHU D  PP WKLFN VWDLQOHVV VWHHO at a speed of 5 mm/h. The relatively high transmission coefficient RI &9/ UDGLDWLRQ DW D JUHHQ ZDYHOHQJWK  ȝP  LQ WKH GHSWK RI VHD ZDWHU PDNHV LW SRVVLEOH WR XVH WKLV ODVHU LQ VXEPDULQH±VDWHOOLWH communication systems and for underwater illumination. Preparation of thin films. The evaporation of the material during its processing by the laser radiation allows this laser to be used to deposit thin films on the selected substrate. The steam flare from the UHPRYHG &9/ PDWHULDO XQGHU ORZ SUHVVXUH  í PP +J  H[SDQGV DQG GHSRVLWV DV D ILOP RQ WKH WDUJHW VXEVWUDWH ,Q >@ ILOPV RI 6E6L 6L DQG *H ZHUH REWDLQHG 7KH DWRPV ZKRVH QXPEHU UHDFKHV  13 ± 14 in a torch, create up to one monolayer per pulse on a VXEVWUDWHORFDWHGDWDGLVWDQFHRI±PPIURPWKHHYDSRUDWLRQVLWH A high deposition rate and good coating properties were obtained on a rotating substrate with radiation defocusing, which created power GHQVLWLHV RI  ā  8 :FP 2. At a substrate velocity of 8 cm/s and a distance of 76 mm to the sprayed material, the deposition rate was QPSHUSXOVH8VLQJWKLVPHWKRGWKHFRDWLQJFDQEHFUHDWHG in a few minutes, whereas the plasma deposition method requires VHYHUDO KRXUV IRU WKLV$W D SHDN SRZHU GHQVLW\ RI  ā  8:FP 3, a ILOPQPWKLFNDQGFPZLGHZDVIRUPHGLQVHFRQGVDQGWKH VXUIDFHURXJKQHVVZDVQRPRUHWKDQQP$—PWKLFNILOPRI silicon was deposited in less than 1 min. The deposition rate in the FDVHRI&9/DSSOLFDWLRQUHDFKHGȝPāFP 2/h, and with the use RI RWKHU ODVHUV LW ZDV RQO\  ȝP ā FP 2/h. Processing of materials by UV radiation of CVL with frequency doubling. CVL with frequency doubling (due to the use of non-linear crystals) can easily generate pulsed energy in the UV range of KXQGUHGVRIPLFURMRXOHVDWDQDYHUDJHUDGLDWLRQSRZHURIDERXW: 7KLVHQHUJ\LVVXIILFLHQWIRUPLFURSURFHVVLQJRUJDQLFSRO\PHUV> ±@ 'XH WR WKH µQRQWKHUPDO¶ QDWXUH RI GULOOLQJ FOHDQ WUHDWHG edges are obtained, without signs of charring and melt of material on the target. Such radiation can process elements with dimensions of only a few micrometers with submicron accuracy. Acryl, glass,

Possibilities of Pulsed Copper Vapour Lasers

51

optical ILEHUSRO\FDUERQDWHSRO\DPLGHSOH[LJODVVVLOLFRQHVLOLFRQH rubber, etc. are included in a number of materials treated with UV radiation of CVL. Such CVLs with UV radiation can be used in the SURGXFWLRQ RI IOH[LEOH PLFURFLUFXLWV SHUIRUDWLRQ RI FDWKHWHUV DQG nozzles for inkjet printers. )RU H[DPSOH LQ RUGHU WR REWDLQ DQ DYHUDJH 89 SRZHU RI  : DW D ZDYHOHQJWK RI  ȝP WKH DYHUDJH SXPS UDGLDWLRQ SRZHU RI WKH &9/ RQ WKH JUHHQ OLQH Ȝ   ȝP  ZDV  : ZLWK D 35) of 4.25 kHz. To increase the quality of the beam, the efficiency and the radiation power of the nonlinear crystal, hydrogen was DGGHG WR WKH &9/ EXIIHU JDV 7R H[FOXGH WKH HIIHFWV RI GLIIUDFWLRQ astigmatism and other distortions, spatial selection of radiation was used. In addition to the fact that CVLs with UV radiation have higher 35) DQG EHDP TXDOLW\ WKH\ DUH PXFK OHVV H[SHQVLYH LQ WHUPV RI investment and maintenance than the base laser installations using XOWUDYLROHW UDGLDWLRQ ± H[FLPHU ODVHUV ,Q DGGLWLRQ WKH 35) LQ &9/ with UV radiation is more than an order of magnitude higher than that of an H[FLPHUODVHUZKLFKVLJQLILFDQWO\LPSURYHVWKHSURFHVVLQJ capacity. 7KHSURFHVVLQJRIWKLQSRO\PHU¿OPVZLWKWKHKHOSRI&9/ZLWK89 radiation is basically similar to the treatment with an H[FLPHUODVHUEXW WKH VSHHG LV  WLPHV JUHDWHU >@ 7KH VSHHG RI DXWRPDWLF GULOOLQJ with such a laser depends mainly on the time required to move the WDUJHW7RGULOODVLQJOHKROHRI±—PLQWUDQVSDUHQWSRO\PHU¿OPV ZLWKDWKLFNQHVVRI—P±PVZDVXVHG7KHVL]HRIWKHKROHFDQ EHEURXJKWXSWRȝPZKLOHWKHHUURULQWKHKROHDUHDLVa In the production of semiconductor devices, the contamination of substrates at the micron and submicron levels results in the rejection of half of the products. The qualitative purification of silicon and glass substrates can be effectively carried out with the help of CVL with UV radiation. UV radiation can also be successfully used in high-performance photolithographic operations for the manufacture or modeling of parts. Thus, the pulsed CVL with respect to the set of parameters is an ideal contactless tool for precision microprocessing a wide range of metallic and non-metallic materials, including transparent ones.

(TXLSPHQWɆɊɏRIOxford Lasers for microprocessing 7KH SURFHVVLQJ HTXLSPHQW 03; LV EDVHG RQ WKH &9/6 RI WKH

52

Laser Precision Microprocessing of Materials

Fig. 2.1. /DVHU WHFKQRORJLFDO XQLW 03; RI 2[IRUG /DVHUV IRU PLFURSURFHVVLQJ PDWHULDOV ZLWK D WKLFNQHVV RI ± PP

Table 2.17KH PDLQ SDUDPHWHUV RI WKH ODVHU SURFHVVLQJ XQLW 03; Parameter

Value

Radiation wavelength, nm

510.6; 578.2

Pulse repetition frequency, kHz

10–12

Duration of radiation pulses (at half-height), ns

20

Average radiation power, W

60

Divergence of radiation beam, mrad

0.075

Power consumption from mains, kW

0.005

Thickness of processed material, mm

0.01–2.00

Working field of the horizontal XY table, mm Vertical Z table, mm

250 100

Accuracy of positioning by X and Y axes, μm, by Z-axis, μm

0.1 0.5

Overall dimensions, mm

1250 × 3250 × 1800

Weight, kg

2400

Possibilities of Pulsed Copper Vapour Lasers

53

02±3$W\SHZLWKWKHSRZHURI:DQGWKHSUHFLVLRQ;@ 7KH PDLQ SDUDPHWHUV RI WKH 03; SODQW DUH VKRZQ LQ 7DEOH  7KH PDLQ DQG VLJQLILFDQW GLVDGYDQWDJH RI 03; LV WKDW WKH AE in the CVLS operate in the continuous pumping mode of the WZRFRPSRQHQW JDV PL[WXUH 1H+&O  LH WKH $( PDQXIDFWXULQJ technology does not provide a sealed operation mode and requires additional life support elements (a pumping pump, gas cylinders, UHGXFHUVFRQWUROVHQVRUVPL[HU ,WLVDOVRNQRZQWKDWWKHRSHUDWLQJ mode reduces the life of the laser and worsens the stability of the output radiation parameters. Disadvantages of the bleeding regime ZHUH FRQILUPHG E\ HPSOR\HHV RI WKH &DQDGLDQ ILUP 3KDV 2SW[ ,QF during a visit to the Istok company (Fryazino, Moscow region). 7KH03;XQLWSXUFKDVHGDQGPDLQWDLQHGE\WKLVFRPSDQ\GLG not provide the required level of output power stability, especially in WKHSURFHVVRISURORQJHGSURFHVVLQJRIFRPSOH[SDUWV:LWKHDFKQHZ DFWLYDWLRQH[WUDFDUHIXOWXQLQJZDVUHTXLUHGWRUHVWRUHWKHRSHUDWLQJ SRZHUOHYHO)RUWKLVUHDVRQ3KDV2SW[,QFSXUFKDVHGIRU03; LQGXVWULDOVHDOHGRII$(.ULVWDOORIWKHPRGHO*/%ZLWKDSRZHU RI:SURGXFHGE\WKHIstok company, which have a high stability of the output parameters.

54

Laser Precision Microprocessing of Materials

2.4. The main results of the first domestic studies on microprocessing at the Kareliya CVLS and installations EM-5029 In Russia (USSR), the first report on the possibility of using CVL IRUPLFURSURFHVVLQJDVPHQWLRQHGGDWHVEDFNWRE\/HEHGHY¶V 3K\VLFV ,QVWLWXWH +RZHYHU H[SHULPHQWDO VWXGLHV RQ WKH DSSOLFDWLRQ of CVL radiation for microprocessing a wide range of thin-sheet PHWDO DQG QRQPHWDOOLF PDWHULDOV ZHUH FDUULHG RXW LQ ± in the framework of the Kareliya project at the Istok company. In this case, a two-channel synchronized CVLS Kareliya operating DFFRUGLQJ WR WKH HIIHFWLYH 02±3)&±3$ VFKHPH ZDV XVHG ZLWK DQ DYHUDJHUDGLDWLRQSRZHURI±:ZLWKD35)RI±N+]DQGD GLIIUDFWLRQ TXDOLW\ RI WKH EHDP >     ±@ ,Q WKHH[SHULPHQWVWKHKareliya CVLS had an average radiation power RI:ZLWKEHDPGLYHUJHQFHRIPUDGș diff PUDG DW N+] 35) > @ 7KH SXOVH GXUDWLRQ ZDV  QV DW D KDOIKHLJKW DQGWKHSXOVHHQHUJ\ZDVP-7KHPDWHULDOVXVHGIRUSURFHVVLQJLQ WKHIRUPRISODWHVîPPLQVL]H ZHUHIL[HGRQWKHFRRUGLQDWH ;WDEOHZKLFKFRXOGPRYHDWDFRQVWDQWVSHHGZLWKLQ±PPV To focus pulsed radiation on the target, lenses with a focal length of 85 to 125 mm were used. In this case, the radiation was focused LQWR D VSRW PHDVXULQJ ± ȝP DQG WKH SHDN SRZHU GHQVLW\ ZDV  ± 11:FP 2. $V D UHVXOW RI WKH H[SHULPHQWV LW ZDV IRXQG WKDW PRO\EGHQXP 0R WXQJVWHQ: WDQWDOXP7D PPWKLFNDUHHIILFLHQWO\FXW DW VSHHGV RI ± PPV VWDLQOHVV VWHHO &U1LɌL  FRSSHU &X  FHUDPLFV IURP DOXPLQXP R[LGH $O 22 3) with thickness up to  PP DOXPLQXP $O  DQG LWV DOOR\V WH[WROLWH GLHOHFWULFV DQG semiconductors, as well as transparent materials. Virtually all of the listed materials were drilled through and through with a thickness RIXSWRPPGXULQJDWLPHRI±V7KHVHVXFFHVVIXOO\FDUULHG RXWILUVWH[SHULPHQWVWHVWLILHGWRWKHSURVSHFWVRIXVLQJWKHUDGLDWLRQ of CVL in technological processes of the production of electronic components. The two-channel CVLS Kareliya was used to fabricate photomasks IRU SULQWHG FLUFXLW ERDUGV E\ HYDSRUDWLQJ D WKLQ ± ȝP  PHWDO coating from a glass substrate with a focused beam of radiation. Such a coating evaporates under the action of one pulse with an energy of ±P-7KH&9/0ZDVXVHGDVDEDVLVIRUWKH(0LQVWDOODWLRQ for high-speed automated production of large-format photomasks on

Possibilities of Pulsed Copper Vapour Lasers

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Fig. 2.2 $ SKRWRPDVN RQ D JODVV VXEVWUDWH PDGH RQ WKH (0 LQVWDOODWLRQ RQ the basis of Kareliya CVLS.

DJODVVZLWKDPDVNLQJFRDWLQJFRSSHUȝPWKLFNQHVVFKURPLXP  7KHPD[LPXPGLPHQVLRQVRIWKHSKRWRPDVNVDUHîPPWKH VSHHG RI WKH SURFHVVLQJ VSRW GLVSODFHPHQW LV XS WR ± PPV Even at such speeds, the processing time, depending on the size and density of the photomask, could be from one to tens of hours. The width of the working line varied from several tens of micrometers WR±PPVWKHURXJKQHVVRIWKHHGJHZDVaȝP 7KHHUURU LQ SRVLWLRQLQJWKHEHDPDORQJWKHZRUNLQJILHOGGLGQRWH[FHHG±ȝP (provided by laser interferometers). Figure 2.2 shows a photomask SURGXFHG RQ WKH LQVWDOODWLRQ (0 ZLWK WKH .DUHOL\D SXOVHG CVLS .

2.5. The first domestic experimental laser installation (ELI) Karavella The first domestic ELI Karavella was created on the basis of pulsed CVLS .DUHOL\DLQ,VWRNFRPSDQ\ >@7KH(/,KDG D ODERUDWRU\ GHVLJQ DQG ZDV LQWHQGHG IRU H[SHULPHQWDO VWXGLHV RQ precision microprocessing of materials for the IET in the field of YDFXXP PLFURZDYH WHFKQRORJ\ > @ Composition and main parameters of the Karavella. The Karavella ELI (Fig. 2.3) consists of several structurally independent units: a two-channel CVLS radiator Kareliya, two upgraded power VXSSOLHV ,3 ZLWK D QDQRVHFRQG V\QFKURQL]DWLRQ V\VWHP WZR

56

Laser Precision Microprocessing of Materials

Fig. 2.3. ELI Karavella for processing materials up to 2 mm thick.

XD[LVKRUL]RQWDOWDEOHVIRUPRYLQJWKHSURFHVVHGPDWHULDODYHUWLFDO table Z for moving the power focusing lens, the numerical control V\VWHP,3&K±WKHWHOHYLVLRQREVHUYDWLRQV\VWHPWKHVXFWLRQ system of the products of material destruction and blowing gas in WKH WUHDWPHQW ]RQH DQG WKH FRQWURO SDQHO >  @ Focusing of radiation of the CVLS on the material to be processed, which is installed on a horizontal XY coordinate table, is made ZLWK DQ DFKURPDWLF OHQV ZLWK D IRFDO OHQJWK RI ± PP 'XH to the movement of the Z vertical table, the focused radiation spot is directed to the surface of the material. The radiation beam is transported to the working lens by an optical system of three rotating flat mirrors. The main parameters of the Karavella ELI are presented in Table 2.2. In the radiator of the Kareliya CVLS working according to the VFKHPH 02±6)&±3$ WKHUH DUH WZR YHUVLRQV RI WKH RSWLFDO V\VWHP with a telescoping unstable resonator (UR) (M    RU ZLWK RQH FRQYH[ PLUURU R 3   RU  FP  LQ WKH PDVWHU RVFLOODWRU :KHQ 85 is used, as the investigations of the intensity distribution in the far field and pulse oscillograms have shown, the output radiation has a WZREHDP VWUXFWXUH ± D FHQWUDO EHDP ZLWK D GLIIUDFWLRQ GLYHUJHQFH  PUDG  DQG D EHDP ZLWK D GLYHUJHQFH RI  QV ǻt  L/c), 15 mrad (Figs. 2.4, a and b  :KHQ XVLQJ DQ RSWLFDO VFKHPH ZLWK a single mirror, the output radiation has a single-beam structure ZLWK D GLYHUJHQFH RI  PUDG ZKLFK LV  WLPHV ODUJHU WKDQ WKH diffraction limit (Figs. 2.4 c and d). In the first case, the density of peak power in the focusing plane of the objective lens with F  PPLV±ā 12:FP2LQWKHVHFRQGā :FP2, i.e. two orders less.

Possibilities of Pulsed Copper Vapour Lasers

57

Table 2.2 The main parameters of the Karavella LTI Parameter

Value

Radiation wavelength, nm

510.6; 578.2

Diameter of radiation beam, mm

20

Average radiation power, W


20

Repetition frequency of pulses, kHz

10 ± 1

Energy at pulse, mJ with telescopic UR (M = 180)* total of individual beams with one convex mirror withy Rz = 3 (or 5) cm Divergence of the radiation beam , mrad with telescopic UR (M =180) with one convex mirror with Rz = 3 (or 5) cm

2 1 2 0,07 (Tdifr); 0.15 0.3 (or 0.5)

Duration of radiation pulses (by half-height), ns with telescopic UR (M = 180): total individual beams with one convex mirror with R = 3 (5) cm Density of peak radiation power in focal spot, W/cm2 with telescopic UR (M = 180) with one convex mirror, Rz = 3 (or 5) cm

15 10 20

(0.57–2.6) · 1012 1.4 · 1010 (or 5 ·109)

Instability of energy at impulse,% with telescopic UR (M = 180) with one convex mirror with Rz = 3 cm Focal distance of the lens, mm Working field of the horizontal table XY, mm Vertical table Z, mm Accuracy of positioning on each axis, μm Gain of the observation system, number of times Power consumption from network, kW

5–10% 1–1.5% 100 140 × 110 200 ±10 × 100 60

Consumption of water, l/min

 @ 7KH HIIHFW RI focused radiation was applied to polished samples of K8 optical glass, fused quartz of KI, KV and KU grades, sapphire, and also artificial polycrystalline diamond. In this case, the destruction of the material occurs both on the surface and in the volume without UHDFKLQJ WKH VXUIDFH :KHQ SURFHVVLQJ LQVLGH D YROXPH WKH HIIHFW of ‘accumulating’ energy takes place, after which destruction begins. The time of such ‘accumulation’ is also related to the distance to the surface of the sample, which suggests the possibility of the influence of near-surface defects on the process of destruction. The peak power density required for the destruction of the materials studied increases LQ WKH VHTXHQFH .±.,±.9±.8±VDSSKLUH 7KH SURFHVVLQJ RI JODVV by means of the radiation of CVL finds practical application mainly in the decorative and artistic area, but can be used for technological purposes: for volumetric marking of serial samples and creation of IL[HG GHIHFWV LQ UHIHUHQFH VDPSOHV RI GLDJQRVWLF HTXLSPHQW > @ A separate important practical task is the processing of diamond materials. Its relevance is connected with the appearance in recent years of artificial polycrystalline diamond plates obtained by deposition from the gas phase. This material (Į T  ā í deg, T m  ƒ&  UHWDLQV LWV GLPHQVLRQV DQG PHFKDQLFDO SURSHUWLHV DW high temperatures, has a high transparency (IJ  DQGDUDGLDWLRQ DEVRUSWLRQ OLPLW RI  ȝP HOHFWULFDO VWUHQJWK  7 V/cm, the work IXQFWLRQLVH9,WVWKHUPDOFRQGXFWLYLW\LV±WLPHVJUHDWHUWKDQ that of copper. Therefore, polycrystalline diamond is a promising PDWHULDO IRU D YDULHW\ RI DSSOLFDWLRQV ± DV VXEVWUDWHV IRU LQWHJUDWHG circuits, windows for the output of high-power microwave energy,

Possibilities of Pulsed Copper Vapour Lasers

65

Table 2.5. The results of the thermal impact on artificial polycrystalline diamond in the treatment with radiation of CVL T °K (not less)

Impact result

1000

Combustion

1700

Graphitization

2300

Fast graphitization

3800

Melting and evaporation

Table 2.6. Threshold values of peak radiation power density for destruction of artificial polycrystalline diamond with different types of pulsed lasers

Laser type

Length wave, μm

Threshold peak power density, n × 108 W/cm2

XeCl

0.31

0.5

CVL

0.51; 0.58

1.2

Nd:YAG

0.53

8

Nd:YAG

1.06

17.5

CO2

10.6

13.2

waveguides, micromechanical devices, cathodes of electrovacuum devices, etc. The presence of various defects in the crystal lattice RIDGLDPRQGZLWKDWRWDOFRQFHQWUDWLRQXSWR21 cm í leads to the appearance of additional absorption levels and photoionization bands, one of which, associated primarily with dislocations and lying in the UHJLRQ ± H9 FRLQFLGHV \LHOGV ZLWK WKH UDGLDWLRQ OLQHV RI WKH CVL. It should be noted that of all forms of carbon only diamond is a dielectric. Any structural change in it leads to the appearance RI FRQGXFWLYLW\:KHQ FRPSDUHG ZLWK RWKHU PHWKRGV RI SURFHVVLQJ precision cutting of graphite by radiation of CVL is recognized as the best. The results of the thermal impact on diamond are shown in Table 2.5. The threshold value of the power density of laser radiation, which causes the destruction of the material, is determined by its nature and concentration of defects. These threshold values for polycrystalline diamond under the influence of nanosecond pulses of different lasers are given in Table 2.6. The threshold value of the radiation power density of CVL for QDWXUDO GLDPRQG LV ±  ā  6 :FP 2, and for a polished plate

66

Laser Precision Microprocessing of Materials

made of artificial polycrystalline diamond obtained by the method of GHSRVLWLRQIURPWKHJDVSKDVHā8:FP2 (see Table 2.6). For a noticeable evaporation of this diamond, it is necessary that the power GHQVLW\ RQ WKH VXUIDFH H[FHHGV  ā  8:FP 2. The average speed of drilling an artificial diamond 1.2 mm thick by CVL radiation with DQHQHUJ\RIP-SXOVHZKHQIRFXVHGLQWRDVSRWZLWKDGLDPHWHURI ±ȝPLV±QPSHUSXOVH3URFHVVLQJRIWKLQVDPSOHVPP  is two orders of magnitude more efficient. The increase in power results in a non-linear increase in processing capacity. A possible prospective direction of technological installations on WKH EDVLV RI &9/ LV PLFURSURFHVVLQJ RI WKLQILOP FRDWLQJV ± microns). Also, there is reason to believe that the use of a fiber-optic cable will allow us to rationally solve the problem of supplying the radiation energy of CVL for vacuum spraying or accelerated dimensional processing of products in chemically active liquids and gas media, which opens the way for the creation of new technological processes and new type installations. The analysis of foreign and domestic literature conducted in this FKDSWHUDQGWKHILUVWH[SHULPHQWDOVWXGLHVRIPLFURSURFHVVLQJLQWKH Karavella ELI allow us to conclude that the pulsed emission of CVL is a promising precision tool for effectively affecting virtually any metallic materials and a large group of dielectrics and conductors, until recently not included in the sphere of laser microprocessing >   ±  @

2.6. Conclusions and results for Chapter 2 1. Laser processing of materials is one of those technologies that determine today the current level of production in the industrialized countries. Its distinctive features are the high quality of the products, high process productivity, saving of human and material resources and environmental cleanliness. Today, the individual technological lasers are not delivered to the PDUNHWEXWGHOLYHUHGDUHWHFKQRORJLFDOXQLWVDQGFRPSOH[HVXVLQJJDV &22 and H[FLPHUODVHUVVROLGVWDWHDQGfiber diode-pumped lasers and diode lasers for dimensional processing, material cutting, welding, surface treatment, alloying, surfacing, marking, engraving, etc. 2. A special place is occupied by laser systems for precision microprocessing, microdrilling, with high resolution marking and engraving, microwelding of the components for electronics. As quality sources of radiation at these systems may effectively be

Possibilities of Pulsed Copper Vapour Lasers

67

XVHG DQG DOUHDG\ DUH XVHG VKRUW SXOVH  QV  KLJKIUHTXHQF\ XSWR±N+] ZLWKVPDOOHQHUJ\DWSXOVH±P- DQGVPDOO UHIOHFWLYLW\ UHIOHFWLRQV ±  DQG KLJK GHQVLW\ SHDN SRZHU ±12:FP2) lasers of the visible and ultraviolet spectrum: solidstate with diode pumping and doubling frequency, gas H[FLPHU DQG QLWURJHQ DQG VSHFLILFDOO\ &9/ ZLWK PHGLXP SRZHU ± : DQG GXUDWLRQ SXOVHV RI ± QV 3. The potential capabilities of the pulsed CVL for processing RI PDWHULDOV IURP XVH RI LQWULQVLF \HOORZ±JUHHQ UDGLDWLRQ DQG 89 UDGLDWLRQ IURP GRXEOHG IUHTXHQF\ ZHUH ILUVW ZLGHO\ H[DPLQHG LQ WKH PRQRJUDSK E\ &( /LWWOH µ0HWDO 9DSRXU /DVHUV¶   ZKLFK included the work of well-known researchers and developers at this region. The monograph presented not only research work, but DOVR FRQFUHWH H[DPSOHV RI WKH SURFHVVLQJ RI PHWDOOLF DQG RUJDQLF materials, semiconductors and dielectrics. At the same time the Istok company using its own CVL, stimulated and conducted studies of the creation of laser technologies for high-quality micromachining of materials for the new generation products for RF-electronics. 4. The first foreign advertised machine with a copper vapour laser designed for productive microprocessing of thin-walled materials ± PP  ZDV WKH ILUVW LQVWDOODWLRQ RI WKH 03; PRGHO developed by the British firm 2[IRUG /DVHUV   7KH GHYLFH LV EDVHG RQ &9/6 RI WKH W\SH PDVWHU RVFLOODWRU±SRZHU DPSOLILHU ZLWK DQDYHUDJHUDGLDWLRQSRZHURI:DQGDSUHFLVLRQ;@ $V D UHVXOW RI WKH DQDO\VLV RI WKH GHVLJQV RI WKH ILUVW $( PRGHOV 7/*   8/   */   DQG */   PDWHULDOV XVHG LQ WKHP SURGXFWLRQ DQG WUDLQLQJ DQG H[FLWDWLRQ FRQGLWLRQV RI WKH SODQW VLJQLILFDQW design and technological defects were found, the reasons for the low efficiency of pumping the AM, and the non-compliance of a number of materials with thermophysical and chemical properties with the requirements for high-temperature AE, which are the reasons for low GXUDELOLW\HIILFLHQF\DQGTXDOLW\RIWKHRXWSXWUDGLDWLRQEHDP>@ The main identified shortcomings of the first industrial sealed-off self-heating AEs are the following: ±WKHF\OLQGULFDOOD\HURIWKHWKHUPDOLQVXODWRUGLUHFWO\VXUURXQGLQJ the high-temperature discharge channel (T chan  ±ƒ&  LQ WKH 7/* DQG 8/$(V LV PDGH RI JULQGLQJ SRZGHU RI$O 2 2 3 R[LGHZLWKIUDFWLRQVL]HVRI±ȝPZLWKUHODWLYHO\KLJKWKHUPDO FRQGXFWLYLW\ Ȝ   :P ā .  DQG VSHFLILF GHQVLW\ p   J cm3 WKHRXWHUVKHOOLQWKH8/*/DQG*/LVDPDVVLYH cermet. The use of these structural materials in the AE led to high power consumption and availability and low efficiency of the CVL; ±WKHH[LWZLQGRZVRIWKH$(DUHPDGHRIXYLROHWWHFKQLFDOJODVV RI 87 EUDQG ZLWK D ODUJH FRQWHQW RI VZLOOV DQG EXEEOHV DQG DUH welded to the end glass sections in the flame of the gas burner and DW DQ DQJOH FORVH WR ƒ ZKLFK OHDGV WR GLVWRUWLRQ RI WKH VWUXFWXUH and poor quality of the output radiation beam; ±ULJLGGHVLJQIRUIDVWHQLQJWKHHQGVRIDKLJKWHPSHUDWXUHFHUDPLF discharge channel to electrode assemblies, limiting the free movement RIWKHFKDQQHODORQJWKH$(D[LVGXULQJLWVKHDWLQJDQGFRROLQJDQG leading to cracking of the channel elements; ±WKHXVHRIDWDQWDOXPVKHOOLQWKHFRSSHUYDSRXUJHQHUDWRUZKLFK causes chemical interaction Ta with ceramic bushings and discharge tubes from Al 22 3, and the use of thin-walled ceramic tubes in the GLVFKDUJHFKDQQHODVLQ7/* GHIRUPLQJHYHQZLWKLQVLJQLILFDQW overheating, lead to premature destruction of the discharge channel and, accordingly, a decrease in the life of the AE; ± WKH DSSOLHG WXQJVWHQ±EDULXP FDWKRGHV KDG D µVPRRWK¶ VXUIDFH which did not provide stable local combustion of a pulsed arc discharge with nanosecond duration and caused instability of the output radiation parameters;

72

Laser Precision Microprocessing of Materials

±DWWKHHQGVRIWKHGLVFKDUJHFKDQQHOWKHUHLVDQDFFXPXODWLRQRI condensed copper droplets overlapping its aperture and reducing the power and distorting the radiation structure. The presence of ‘large’ drops indicates an incorrect location of copper vapour condensers and a poorly designed structure of the near-electrode region of the AE; ±ORZRXWSXWSRZHU±: DQGHIILFLHQF\± GXHWR ORZ SXPSLQJ HIILFLHQF\ DQG KLJK SRZHU FRQVXPSWLRQ RI$( ± N:  7KH HOHFWULFDO FLUFXLW RI WKH KLJKYROWDJH SXPS PRGXODWRU RI the laser power source is made according to the classical (direct) scheme. In this case, the high-voltage pulse commutator (hydrogen thyratron), the storage capacitor and the AE form a single discharge circuit, when the duration of the leading edge and the total duration of the generated pump current pulses are determined mainly by WKH FKDUDFWHULVWLFV RI WKH WK\UDWURQ DQG DUH DERXW  DQG  QV UHVSHFWLYHO\ZKLFKLVQRWVXIILFLHQWIRUHIIHFWLYHFRQGLWLRQVH[FLWDWLRQ of AS; ± UHGXFWLRQ RI WKH RXWSXW UDGLDWLRQ SRZHU GXULQJ WKH RSHUDWLRQ of the CVL, due to the imperfection of the developed technology RI WUDLQLQJ IRU GHJDVVLQJ WKH$( DQG GXVWLQJ LWV H[LW ZLQGRZV ZLWK vapours of the working substance (copper), products of erosion of the electrodes and the discharge channel; ±ORZJXDUDQWHHGRSHUDWLQJWLPHRI$(FDXVHGE\DQXPEHURIWKH above-mentioned shortcomings (criterion according to TU (Technical ,QVWUXFWLRQV  ± UHGXFWLRQ RI WKH UDGLDWLRQ SRZHU LV QRW PRUH WKDQ   ± K ± UXQQLQJ RI $( RI WKH PRGHOV 7/* DQG 8/ K±RSHUDWLQJKRXUVRI$(VRIWKHPRGHOV*/DQG Despite the relatively low values of longevity, efficiency and quality of radiation of the first industrial sealed-off self-heating $(V RI WKH SXOVHG &9/ PRGHOV 7*/ 8/ */ DQG */ >@DVVRFLDWHGZLWKDQXPEHURIµXQVXFFHVVIXO¶GHVLJQ DQG technological solutions, the use of a low-efficiency heat insulator and output windows with low quality, the absence of electrical circuits of a high-voltage modulator of the power source for the formation of short-pulse pump currents with steep fronts, of the structure and the spatiotemporal and energy characteristics of the output radiation from WKHH[FLWDWLRQFRQGLWLRQVRIWKHDFWLYHPHGLXPSRZHUFRQVXPSWLRQ pump pulse parameters, pulse repetition frequency, discharge channel temperature, neon buffer gas pressure, hydrogen additives), the type RI RSWLFDO UHVRQDWRU DQG LWV SDUDPHWHUV GXUDELOLW\ WHVWV WR ±  WKH LVVXH RI WKH IXUWKHU GHYHORSPHQW RI SXOVHG &9/V EHFDPH increasingly urgent.

New Generation of Efficient Sealed-off Active Elements

73

At that time, the main areas of application of pulsed CVLs in science, engineering and medicine were outlined and the main promising directions were identified, in which the greatest efficiency LV DFKLHYHG ZLWK WKH KHOS RI WKH &9/ >±@ ,Q VXFK SURPLVLQJ areas of pulsed CVL application, it is necessary to include the precision microprocessing of materials for electronic products, the VHSDUDWLRQRILVRWRSHVIRUH[DPSOH 235U uranium enrichment) and the production of high-purity substances for the needs of nuclear energy and medicine, the pumping of wavelength-tunable lasers on dye solutions (DSL), laser projection microscopy (intensification of the image brightness of microobjects), spectral analysis and diagnostics of the composition of substances, sounding of the atmosphere and sea depths, logical and non-neoplastic diseases by photodynamic therapy, dermatology and cosmetology and others. This was the LPSHWXV WR FDUU\ RXW H[WHQVLYH UHVHDUFK DLPHG DW LPSURYLQJ WKH FKDUDFWHULVWLFV RI WKH &9/$OUHDG\ LQ ± LQ &9/V ZLWK DQ unstable resonator of the telescopic type, beams with a diffraction divergence were obtained with an increase of hundreds of times >±@ DQG LQ  >@ LW ZDV UHSRUWHG WKDW DQ DYHUDJH UDGLDWLRQ SRZHU RI  : ZLWK D SUDFWLFDO HIILFLHQF\ RI a DW WKH 35) XS WR  N+] %\  WKH Lawrence Livermore National Laboratory (LLNL) constructed an CVLS, working according to the master RVFLOODWRU±SRZHUDPSOLILHUVFKHPHRXWRI$(VZLWKDWRWDORXWSXW SRZHURI:ZLWKLQWKH$9/,6SURJUDP >@$GHWDLOHGUHYLHZ of the state and development of pulsed CVLs is given in Ch. 1.

3.2. Investigation of ways to increase the efficiency, power and stability of the output radiation parameters of CVL To determine the ways of increasing the power, efficiency and stability of the output radiation parameters of sealed-off self-heating $(VH[SHULPHQWDOVWXGLHVZHUHFDUULHGRXWRI&9/ZLWKWKH.ULVWDOO LQGXVWULDO $( RI WKH */ PRGHO DQG WKH H[SHULPHQWDO .ULVWDOO RI WKH */' DQG */' W\SH ZKLFK DUH WKH ILUVW PRVW powerful sealed-off self-heating AEs with copper vapour generators with a tantalum sheath, with free copper disposition in the discharge FKDQQHOZLWKSVHXGRDOOR\VRIWKHFRPSRVLWLRQ:±&XDQG0R±&XDQG generators on a molybdenum substrate at pressures of the buffer gas RIQHRQLQWKHUDQJHRI±PP+JDQGIL[HG35)ZLWKGLIIHUHQW HOHFWULFDOFLUFXLWVIRUWKHH[HFXWLRQRIDKLJKYROWDJHSXOVHPRGXODWRU

74

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RI WKH 3,'$OO UHVHDUFK UHVXOWV KDYH EHHQ ZLGHO\ SUHVHQWHG LQ FR DXWKRUVKLS LQ WKH PRQRJUDSK > &K @ The structures of the Kristall AE used for the first time a nonFRQGXFWLYHPHWDOSRURXV:±%DFDWKRGHZLWKDQDFWLYHVXEVWDQFHRI WKHFRPSRVLWLRQ%D2ā$O223ā&D2ā6L22 (barium aluminosilicate) of a ring structure and with an annular groove on the inner working surface with which the first positive results on stable local combustion of a pulsed arc discharge in the auto-thermoemission regime, a two-layer high-temperature heat insulator with a low FRHIILFLHQWRIWKHUPDOFRQGXFWLYLW\Ȝ ±:Pā. ORFDWHG between the discharge channel, a vacuum-tight envelope and the electrode assemblies, the two-stage training technique for degassing DQGFOHDQLQJLWXSWRKRXUVDOORZHGWRSUHVHUYHWKHSXULW\RIWKH JDVHRXV PHGLXP QHRQ  IRU RYHU  KRXUV $FRPSDUDWLYHDQDO\VLVRIWKHH[SHULPHQWDOGDWDRQWKHSXPSLQJ HIILFLHQF\ RI WKH &9/$( ZLWK GLIIHUHQW H[HFXWLRQ RI WKH HOHFWULFDO circuit of the high-voltage pulse modulator of the power source was carried out and it was found that with the electric circuit of the capacitive voltage doubling and the magnetic links of the current pulse compression in comparison with the direct classical highvoltage modulator of the power source and when using a hydrogen thyratron as a high-voltage pulse commutator the duration of GLVFKDUJH FXUUHQW SXOVHV LQ WKH $( ZDV KDOYHG IURP ± QV WR ± QV  ZKLFK OHDGV WR DQ LQFUHDVH LQ WKH UDGLDWLRQ SRZHU and efficiency by about 2 times due to an increase in the optimum FRQFHQWUDWLRQRIFRSSHUYDSRXULQWKHDFWLYHPHGLXPE\DERXW± times (the operating temperature of the discharge channel increases), WKH VHUYLFH OLIH RI WKH SXOVHG K\GURJHQ WK\UDWURQ XS WR ± K  DQG WKH VZLWFKHG SRZHU XS WR ± N:  DUH PXOWLSOLHG VHYHUDO times due to a reduction of the power losses in the thyratron, which is a high-voltage commutator. The power source with this scheme ZRUNV VWHDGLO\ LQ WKH 35) UDQJH RI ± N+] WKH DPSOLWXGHV RI WKH YROWDJH SXOVHV ± N9 DQG WKH GLVFKDUJH FXUUHQW RI ± N$ ZLWK D OHDGLQJ HGJH GXUDWLRQ RI ± QV ZLWK D EDVH GXUDWLRQ RI ± QV WKH DGYDQWDJH RI WKH HOHFWULFDO FLUFXLW RI WKH SRZHU VRXUFHPRGXODWRUZLWKD*,$YDFXXPODPSDVDKLJKYROWDJHSXOVH commutator is the possibility of forming current pulses with a front GXUDWLRQ RI ± QV DW D WRWDO GXUDWLRQ RI ± QV FRPPHQVXUDWH ZLWK WKH WLPH RI SRSXODWLRQ LQYHUVLRQ H[LVWHQFH DW YROWDJHV RI ±  N9 DQG 35) WHQV DQG KXQGUHGV RI N+] DQG DFFRUGLQJO\ WKH SRVVLELOLW\ RI DFKLHYLQJ PD[LPXP YDOXHV RI UDGLDWLRQ SRZHU DQG

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efficiency, the disadvantage is that the amplitude of the current pulses GRHVQRWH[FHHGYDOXHVJUHDWHUWKDQ$EHFDXVHRIWKHOLPLWDWLRQ of saturation current. 7KH PD[LPXP HIILFLHQF\ DQG RXWSXW SRZHU RI WKH &9/ ZLWK WKH .ULVWDOO $( RI WKH PRGHOV */ */' DQG */' LQ the sealed-off mode (especially at low neon pressures in the AE ± ± PP +J  LV DFKLHYHG ZLWK FRSSHU YDSRXU JHQHUDWRUV RQ a molybdenum substrate after their reduction by hydrogen at the working temperature of the discharge channel (Tchanaƒ& ZKLFK is carried out after a full cycle of two-stage degassing of the AE. At pressures of the buffer gas of neon in the AE in the range ±PP+JDGGLWLRQVRISXUHK\GURJHQZLWKDSDUWLDOSUHVVXUHXS WRPP+J OHDGWRDQLQFUHDVHLQWKHUDGLDWLRQSRZHUE\WLPHV or more, at pressures of neon close to atmospheric and at atmospheric pressure hydrogen has no appreciable effect on the radiation power. :KHQ WKH QHRQ SUHVVXUH LQ WKH $( YDULHV IURP  WR  PP Hg, and the optimum power consumption from the power source, WKHUDGLDWLRQSRZHUGHFUHDVHVPRQRWRQLFDOO\)RUH[DPSOHZLWKWKH LQGXVWULDO $( */ DW  N+] 35) WKH WRWDO DYHUDJH UDGLDWLRQ SRZHULVUHGXFHGIURP:DWDSUDFWLFDOHIILFLHQF\RIa WR :HIILFLHQF\a 7KHGHFUHDVHLQWKHWRWDOUDGLDWLRQSRZHU LV PDLQO\ GXH WR D GHFUHDVH LQ SRZHU DW WKH JUHHQ ZDYHOHQJWK Ȝ  ȝP VLQFHWKHH[FLWDWLRQFRQGLWLRQVGHWHULRUDWHZLWKLQFUHDVLQJ SUHVVXUH7KH SRZHU RQ WKH \HOORZ OLQH Ȝ   ȝP  YDULHV OLWWOH :LWK RSWLPXP SRZHU FRQVXPSWLRQ WKH HIILFLHQF\ RI WKH VHDOHG RII$(V SI WKH &9/ RI WKH .ULVWDOO VHULHV LV DSSUR[LPDWHO\  WLPHV JUHDWHU WKDQ WKH SUDFWLFDO HIILFLHQF\ RI WKH ODVHU DQG LV DERXW  DW UHODWLYHO\ ORZ QHRQ SUHVVXUHV DQG  DW DWPRVSKHULF SUHVVXUH ,W KDV EHHQ H[SHULPHQWDOO\ HVWDEOLVKHG WKDW WKH KLJKHVW YDOXHV RI efficiency in CVL can be achieved with power consumption less than optimal values, but with the condition of maintaining a high RSHUDWLQJWHPSHUDWXUHRIWKHGLVFKDUJHFKDQQHOaƒ& :LWKWKH DFWLYH HOHPHQW */ LQ WUDQVLHQW RSHUDWLRQ PRGHV LW ZDV VKRZQ WKDW LW LV SRVVLEOH WR REWDLQ D SUDFWLFDO ODVHU HIILFLHQF\ XS WR  DQ HIILFLHQF\ IDFWRU RI$( WR  At pressures of the buffer gas of neon in the AE of the CVL close to atmospheric and at atmospheric pressure, to obtain values of the radiation power commensurate with the values at low pressures, the LQWHQVLW\ LQ WKH JDVGLVFKDUJH JDS RI WKH $( VKRXOG EH DW OHDVW  kV/m when current pulses with a front duration of not more than QVZLWKDWRWDOGXUDWLRQRI@ ZDV FUHDWHG with twice the efficiency and minimum operating time. Due to the decline of domestic microelectronics, the demand for laser image

New Generation of Efficient Sealed-off Active Elements

77

Fig. 3.2. The first industrial sealed-off self-heating laser AEs on copper vapours: .ULVWDOO */  .YDQW 8/  .XORQ */  IURP WRS WR ERWWRP 

amplifiers of microobjects has fallen, and this class of devices has not been further developed. 7KH .XORQ $( RI WKH PRGHO */ ZLWK DQ DYHUDJH UDGLDWLRQ SRZHU RI ± : EHFDPH WKH EDVLV IRU WKH GHYHORSPHQW RI WKH direction of low-power AEs of the CVL. A new generation of small-sized industrial sealed self-heating AE series Kulon and based on them the CVL with air or water cooling, designed for the technological and medical research of the composition of substances, spectroscopic studies, nanotechnology, etc. has been developed. 7RGD\WKH$(V.XORQ*/DFFRUGLQJWRWKH7HFKQLFDO,QVWUXFWLRQV 78  RQ FRSSHU YDSRXU ZLWK DQ DYHUDJH UDGLDWLRQ SRZHU RI ±: DQG RQ JROG YDSRXU ZLWK D SRZHU RI ± : >   ±@ are produced. The second direction, which has been successfully developed, is the development of a new generation of industrial sealed-off selfKHDWLQJ$(VHULHV.ULVWDOO*/DFFRUGLQJWR78 RQWKHEDVLVRI WKH ILUVW VHDOHGRII VHOIKHDWLQJ$( RI WKH .ULVWDOO PRGHOV */ */'DQG*/'ZLWKWKHDYHUDJHSRZHURIUDGLDWLRQRI± :7KLVVHULHVRILQGXVWULDO$(VLVPDLQO\XVHGLQSXOVHG&9/6 RI WKH 02±3$ W\SH LQWHQGHG IRU PRGHUQ WHFKQRORJLFDO HTXLSPHQW IRU SUHFLVLRQ PLFURSURFHVVLQJ RI µWKLFNSODWH¶ PDWHULDOV ± PP  isotope separation and production of highly pure substances for QXFOHDU SRZHU DQG PHGLFLQH HWF >   ± ± ±@

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3.4. Appearance and weight and dimensions of industrial sealed-off AEs of the pulsed CVL of the Kulon and Kristall series A new generation of industrial sealed-off self-heating AEs of the SXOVHG &9/ .XORQ VHULHV RI ORZ SRZHU ± :  DQG WKH .ULVWDOO VHULHVRIWKHDYHUDJHSRZHUOHYHO±: ZDVILUVWGHYHORSHGDQG prepared for serial production over the last decade in the laboratory Lasers and laser technologies of the Istok Co (Fryazino, Moscow region). The work to improve design and technology of AE training, in order to further improve their durability, efficiency, quality and stability of output parameters, continue to this day. Appearance of the new generation of industrial AE series Kulon and Kristall pulsed CVLs is shown in Fig. 3.3. Conventional designation of the AE series Kulon in terms of technical VSHFLILFDWLRQV 78  ± */$ */% */& */* */'*/(*/=+DQG*/,.ULVWDOOVHULHV±*/ $ */% */9 */=+ DQG */* >  ±± ±@ 7KH RSHUDWLQJ SRVLWLRQ RI WKH $( LV KRUL]RQWDO DQG IL[HG XVXDOO\ EHKLQG WKH FRQQHFWLQJ SRLQWV LQ WKH HOHFWURGH DVVHPEOLHV LQ )LJV  DQG  ± WKH VL]H a). In Fig. 3.4 LVDVFKHPDWLFUHSUHVHQWDWLRQLQ7DEOH±RYHUDOODQGFRQQHFWLQJ dimensions and weight of new industrial sealed AE of the Kulon VHULHV)LJXUHLVDVFKHPDWLFUHSUHVHQWDWLRQLQ7DEOH±RYHUDOO

Fig. 3.3. Appearance of industrial self-heating sealed-off laser active elements on FRSSHUYDSRXURIWKH.XORQVHULHVZLWKORZSRZHU±: DQG.ULVWDOORIPHGLXP SRZHU ±: 

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L2, mm

D1, mm

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L1, mm

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and connecting dimensions and mass of new industrial sealed selfheating AE series Kristall. From the AEs of the Kulon series, the minimal dimensions and ZHLJKWDUHWKRVHRIWKH*/$PRGHOL1 PPD1 PP D2 PPM NJ PD[LPXP±PRGHO*/-L1 PP D1 PPD2 PPM NJ )URPWKH$(VRIWKH.ULVWDOO VHULHV WKH PLQLPXP GLPHQVLRQV DQG ZHLJKWV DUH WKRVH RI WKH */ $ PRGHO L 1   PP D 1   PP D 2   PP M   NJ  PD[LPXP ± PRGHO /7&X L 1   PP D 1   PP D 2   PP M   NJ 

3.5. Construction, manufacturing and training technology, basic parameters and characteristics of industrial sealed-off AEs of the Kulon and Kristall CVL series The AEs of the pulsed CVLs are high-voltage gas discharge devices operating in the pulsed arc discharge mode and at high temperatures. As the basic structural materials in industrial sealed-off AEs of the new generation are the materials and technologies widely used in the electrovacuum applications, in particular, in the electrovacuum microwave equipment produced by the Istok company were used. In the design of the sections, in the technology of manufacturing and training of self-heating AEs of new industrial models, all WKH SRVLWLYH UHVXOWV WKDW ZHUH DFKLHYHG GXULQJ WKH  \HDUV RI

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H[SHULPHQWDO DQG WKHRUHWLFDO VWXGLHV RI &9/ ZHUH XVHG7KH UHVXOWV RI WKHVH VWXGLHV DUH JHQHUDOL]HG DQG SUHVHQWHG LQ > @ 7KH developed sealed-off AE of the Kulon and Kristall series, despite the relatively large difference in power, have identical design, manufacturing technology and training in degassing and cleaning. The AEs and their main functional units are practically different only in overall dimensions, mass and duration of the process for degassing and cleaning. New industrial models of the AEs of the Kulon and Kristall differ from the first generation by lower power consumption, higher power output and efficiency, service life, quality, stability and reproducibility of the output beam parameters. 0D[LPXPHIILFLHQF\SRZHUDQGGXUDELOLW\KLJKVWDELOLW\RISRZHU DQG D[LV RI WKH UDGLDWLRQ SDWWHUQ DQG KLJK TXDOLW\ RI UDGLDWLRQ LQ LQGXVWULDO VHDOHGRII VHOIKHDWLQJ $(V RI WKH .XORQ ± :  DQG .ULVWDOO±: VHULHVRIWKHSXOVHG&9/VDUHDFKLHYHGGXHWR ± XVLQJ D FHUDPLF GLVFKDUJH FKDQQHO ZLWK EOLQG JURRYHV LQ HDFK of which a copper vapour generator is installed in the form of a PRO\EGHQXP VXEVWUDWH ZLWK KROHV ZHWWHG E\ WKH DFWLYH VXEVWDQFH ± molten copper and perforated end tubes; ± WKH GHYHORSHG WHFKQRORJ\ IRU VXUIDFH SXULILFDWLRQ RI FRSSHU vapour generators in a hydrogen atmosphere with neon at T work  ƒ& DIWHU FRPSOHWH GHJDVVLQJ RI$( DW T  ƒ& ZLWK D GXUDWLRQ RI ± K GHSHQGLQJ RQ WKH$( PRGHO  ±FUHDWLRQRIDQRQVSDUNDXWRWKHUPLRQLFPHWDOSRURXVWXQJVWHQ EDULXP :±%D  FDWKRGH RI D ULQJ VWUXFWXUH ZLWK DQ DQQXODU JURRYH on the inner surface; ± DSSOLFDWLRQ RI RXWSXW HQOLJKWHQHG ZLQGRZV ZLWK DQ DQJOH RI LQFOLQDWLRQ WR WKH RSWLFDO D[LV RI WKH$( QRW H[FHHGLQJ WKH YDOXHV v arctg

(2  ab) , ( 2a  b)

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where a  D ch/l ch (D ch is the diameter and l ch is the length of the discharge channel), b D ch/l w (l w is the distance from the end of the GLVFKDUJH FKDQQHO WR WKH ZLQGRZ DORQJ WKH RSWLFDO D[LV  The design of industrial AEs is protected by 4 patents of the 5XVVLDQ )HGHUDWLRQ 1R    1R  1R  DQG 1R  The design, manufacturing and training technology of AEs of the Kulon series with a power of 1–20 W. The design of industrial

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Fig. 3.6. Design of industrial sealed-off self-heating laser AE of the Kulon series of the pulsed CVL: 1±VHFWLRQHGGLVFKDUJHFKDQQHO2±GLVFKDUJHFKDQQHOWXEHV3± connecting bushings; 4±FRSSHUYDSRXUJHQHUDWRUV5±FRSSHUYDSRXUFRQGHQVHUV 6 ± QHDUHOHFWURGH HQG  WXEHV 7 ± FDWKRGH KROGHU 8 ± FDWKRGH 9 ± DQRGH 10 ± electrode cups; 11±DOXPLQRSKRVSKDWHFHPHQW$3& 12±KLJKWHPSHUDWXUHVHDOLQJ cement; 13, 14, 15 ± WKUHHOD\HU KHDW LQVXODWRU 16 ± YDFXXPWLJKW VKHOO 17, 18, 19 ± PHWDO FXSV 20 ± HQG VHFWLRQV 21 ± RXWSXW ZLQGRZV 22 ± VFUHHQWUDSV 23 ± glass tubes; 24 ± PHWDO OREHV

sealed-off self-heating AE of the Kulon series of the pulsed CVL is shown in Fig. 3.6. 7KH RXWHU SDUW RI WKH $( VWUXFWXUH LV D F\OLQGULFDO PHWDO±JODVV casing (item 16) with optical windows (item 21) on the ends for laser output and metal lobes (item 24) on the electrodes for connection of high-voltage pulse from the power source. The envelope of the AE is vacuum-tight and is the carrier of the entire structure, installed KRUL]RQWDOO\ RQ WKH PHWDO FXSV LWHP   2Q WKH $( D[LV WKHUH LV a sectioned discharge channel (position 1, 2, 3) with generators (item 4) of copper vapour in the blind grooves (joints of tubes with bushings) and condensers (position 5), electrode sections at its ends   ZLWK DQ DQQXODU FDWKRGH LWHP   DQG DQ DQRGH LWHP   LQ WKH VSDFH EHWZHHQ WKH PHWDO±JODVV VKHDWK LWHP   WKH GLVFKDUJH FKDQQHO LWHP   DQG HOHFWURGH DVVHPEOLHV LWHP   ± D WKUHHOD\HU heat insulator (positions 13, 14 and 15). The partitioned discharge channel (position 1) of the AE, as can be seen from Fig. 3.6, consists of ceramic tubes (item 2), interconnected by ceramic bushings (item 3), two or three copper vapour generators (item 4), two copper molybdenum vapour condensers (item 5) and two near-electrode ceramic tubes (item 6). The gaps in the joints of ceramic pipes (item 2) with bushings (item 3) are sealed with KLJKWHPSHUDWXUH FHPHQW LWHP   IURP ILQH SRZGHU ± Al 22 3  ± 7L2 2 :KHQ WUDLQLQJ WKH $(V IRU GHJDVVLQJ ZKHQ WKH WHPSHUDWXUH RI WKH GLVFKDUJH FKDQQHO ULVHV WR ±ƒ& cement is caked. The design of the discharge channel becomes

New Generation of Efficient Sealed-off Active Elements

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integral and mechanically rigid and removal of copper vapour from the active volume through the gaps in the joints is prevented. (The design of a sectioned ceramic discharge channel with copper vapour JHQHUDWRUV LV SURWHFWHG E\ SDWHQW 1R    5) µ'LVFKDUJH WXEH RI D PHWDO YDSRXU ODVHU¶ >@ $W WKH VDPH WLPH GHSOHWLRQ RI the active substance from generators (item 4) is determined by the diffusion loss of copper vapour along the discharge channel to its relatively cold ends, where the perforated condensers are located (position 5). The service life of the AE is determined by the formula t

m , D ( N / l ) SJ

(3.2)

where m is the mass of copper in the generators (g), D is the diffusion coefficient of copper (cm2V >@N is the concentration of copper vapour in the generator region (cm±), l is the distance from the generators to the copper vapour condensers (cm), S is the area of the aperture of the discharge channel (cm 2 DQGȖLVWKHPDVVRI the copper atom (g). As a material of the tubes (items 2 and 6) and bushings (item 3) of the discharge channel (item 1) with an operating temperature of XSWRƒ&E\PHDQVRIDFRPSURPLVHDQDO\VLVRIWKHSURSHUWLHV RIKLJKWHPSHUDWXUHR[LGHVZDV$FHUDPLFVRIWKHFRPSRVLWLRQ $O 22 3  0J2 ZLWK D PHOWLQJ SRLQW RI ƒ& SURGXFHG 10

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Fig. 3.7. Fragment of the discharge channel with cathode node of laser AE of the Kulon series: 1±VHFWLRQHGGLVFKDUJHFKDQQHO2±DWXEHRIWKHGLVFKDUJHFKDQQHO 3±FRQQHFWLQJVOHHYH4±PRO\EGHQXPVXEVWUDWH5±FRQGHQVHURIFRSSHUYDSRXU 6±QHDUHOHFWURGHWHUPLQDO WXEH7±FDWKRGHKROGHU8±FDWKRGH9±FRSSHUULQJ 10 ± EDVH RI WKH HOHFWURGH FXS 11 ± DOXPLQRSKRVSKDWH FHPHQW $3&  12 ± KLJK temperature sealing cement; 13, 14 and 15±UHVWULFWLYHPRO\EGHQXPULQJVDQGZLUH 16 ± D IRLO PRO\EGHQXP GLVN

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by the ,VWRN &R > &K @ $OWKRXJK DV UHJDUGV WKH SK\VLFR chemical properties the preferred material for tubes and bushings RI WKH GLVFKDUJH FKDQQHO LV FHUDPLFV IURP EHU\OOLXP R[LGH %H2  >@7KHPHOWLQJSRLQWRIFHUDPLFVIURP%H2LVDERYHƒ&WKH vapour pressure of the compound at operating temperature is less WKDQ± mm Hg (Al223±íPP+J 7KH%H2R[LGHLQFRPSDULVRQ with Al 2 2 3 has 2.5 times higher thermal conductivity (14.5 and  :PāGHJ  DQG  WLPHV OHVV VSHFLILF JUDYLW\ ± DQG  ± JFP 3) and, accordingly, better withstands thermal shock GXULQJ KHDWLQJ %XW WKH EHU\OOLXP R[LGH KDV D VLJQLILFDQW GUDZEDFN ±KLJKWR[LFLW\ZKLFKFUHDWHVVHULRXVWHFKQRORJLFDOSUREOHPVLQWKH manufacture of devices. In addition, in Russia the production of FHUDPLFWXEHVIURP%H2GRHVQRWH[LVWDQ\PRUHDQGLWLVH[SHQVLYH For a more precise representation of the design of the partitioned discharge channel Fig. 3.7 shows its enlarged fragment with the cathode unit adjacent to its end. The aperture of the discharge channel (item 1) and the active medium (AM), respectively, is determined by the internal diameter of its tubes (item 2), the length of the discharge channel is the distance between the cathode (item   DQG WKH DQRGH LWHP   WKH OHQJWK RI WKH DFWLYH PHGLXP E\ WKH distance between the condensers of copper vapour (item 5). ,Q WKH FRXUVH RI WKLV ZRUN VL[ $( PRGHOV RQ FRSSHU YDSRXUV and two models on gold vapours with different diameters and the length of the discharge channel were developed and investigated. ,Q WKH ORZSRZHU$( PRGHOV */$ DQG */% WKH DSHUWXUH RI WKH GLVFKDUJH FKDQQHO ZDV  PP LQ */& ±  PP */ ( DQG */, ±  PP 7KH OHQJWK RI WKH µFROG¶ GLVFKDUJH FKDQQHO RI WKHVH$(V DQG LWV DFWLYH PHGLXP ZDV  DQG  PP  DQG  PP  DQG  PP  DQG  PP  DQG  mm, respectively. The volume of the active medium, defined as the product of the channel aperture by the length of the active medium, IRU$( */$ ZDV  FP 3 IRU */%   FP 3 */&  28 cm 3 */(   FP 3 DQG */-   FP 3. In the operating mode, the relative elongation of the discharge FKDQQHOIRUWKH$(RI*/$ZLWKDWHPSHUDWXUHTchanaƒ&LV 7 1 DERXWPPFRHIILFLHQWRIWKHUPDOH[SDQVLRQ D 7$O223 ā . */% ±  PP */±& ZLWK T chan a Û&  PP */ (ZLWKTchanaƒ&±PPDQG*/-±PP7KLQZDOO SHUIRUDWHGEDVHSODWHVRIHOHFWURGHDVVHPEOLHVLWHP SOD\WKHUROH of membranes that provide relatively free movement of the discharge FKDQQHO ZKHQ LW LV KHDWHG DQG FRROHG DORQJ WKH D[LV RI WKH$(

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Copper vapour generators (item 4 in Fig. 3.6) are placed on the connecting ceramic sleeves (item 3), in the space between the tubes (position 2) of the discharge channel, without overlapping the channel aperture. They consist of a cylindrical molybdenum substrate (item 4 in Fig. 3.6) that is directly adjacent to the inner surface of the connecting sleeve (item 3), the side restricting disk of molybdenum LWHP   DQG WKH FRSSHU ULQJ LWHP   DV WKH DFWLYH VXEVWDQFH 0RO\EGHQXP 0&K93 LV XVHG FRSSHU JUDGH 09 RU 0RE 7KH IDFW WKDWPRO\EGHQXPLVFKRVHQDVWKHVXEVWUDWHPDWHULDOLVH[SODLQHGE\ its two positive properties: firstly, high wettability by molten copper and, secondly, it does not interact with ceramics from alumina [16, &K@>&K@7KHFRSSHUYDSRXUJHQHUDWRUVRIWKLVGHVLJQDQG such composition, in terms of their physico-chemical properties and efficiency, fully comply with the discharge requirements channel with operating temperature Twork ±ƒ&$WWKLVWHPSHUDWXUH molybdenum is well wetted by molten copper and spreads over the surface of the molybdenum substrate (item 4 in Fig. 3.7). But usually, after the end of the many hours of training of the AEs for its degassing in a discharge with the pumping of the buffer gas, the PROWHQFRSSHULWHPLQ)LJ GRHVQRWVSUHDGRYHUWKHVXUIDFHRI the substrate (item 4), but accumulates in its lower part in the form of a cusp with a ‘ragged’ and uneven shape, significantly overlapping the aperture of the discharge channel. In the process of training, there is a strong gas separation, mainly from the heat insulator and the formation of metal vapours and, naturally, contamination occurs, LQFOXGLQJUHIUDFWRU\R[LGHVRIWKHVXUIDFHVRIERWKWKHPRO\EGHQXP substrate and molten copper. Even the heating of the channel to ƒ& GLG QRW OHDG WR WKH GHVLUHG HIIHFW ,Q RUGHU WR UHVWRUH WKH VXUIDFH RI PHWDOV IURP R[LGHV WR WKH ZRUNLQJ YROXPH RI WKH $( KLJKSXULW\ PROHFXODU K\GURJHQ ZLWK D SDUWLDO SUHVVXUH RI XS WR  mm Hg is introduced (until the generation disappears completely). After holding for a certain period of time high-purity neon is pumped through the AE in the operating mode until the ‘contaminated’ gas PL[WXUHLVFRPSOHWHO\SXULILHG,IWKHPROWHQFRSSHUGRHVQRWVSUHDG over the molybdenum surface or even spreads, but no increase in the radiation power is observed, then the technological process is repeated. The process of hydrogen purification is repeated until full ZHWWLQJRFFXUVDQGWKHUDGLDWLRQSRZHUGRHVQRWUHDFKLWVPD[LPXP value, which in turn attests to the achievement of a high degree of purity of the surface of the molybdenum substrate and molten copper and, accordingly, the evaporation rate of copper vapour. The

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efficiency of the AEs with pure copper vapour generators increases significantly with a decrease in the working pressure of neon, for H[DPSOH IURP ± PP +J XS WR ± PP +J ,W ZDV DOVR observed that the addition of several mm Hg of pure hydrogen in the AE after its complete purification leads to an additional increase in efficiency and radiation power. Condensers of copper vapour (item 5) are molybdenum bushings with a perforated section (with holes) located in the condensation zone of copper vapour, between the electrode tubes (item 6) and the discharge channel pipes (item 2) (item 1). The holes are designed for free passage of copper vapours from the condensation zone to the fibrous heat insulator VKV-1, which prevents the formation of copper droplets at the ends of the discharge channel and, as D FRQVHTXHQFH WKH RYHUODSSLQJ RI LWV DSHUWXUH 2YHUODSSLQJ WKH aperture with droplets of copper degrades the quality of the radiation beam and reduces its power. (The design is protected by the author’s certificate No. 1 572 367 of the USSR ‘Active element of a laser RQ YDSRXUV RI FKHPLFDO VXEVWDQFHV¶ >@  7KH GHVLJQ ZRUNV DV follows. The active substance (copper) vapour under the action of longitudinally directed temperature and concentration gradients diffuses along the discharge channel from its central high-temperature part to the colder ends. Reaching the perforation zone, the copper vapours under the action of a radially directed temperature gradient deviate to the walls of the tube and through the holes diffuse into the heat insulator, where they condense, i.e., beyond the aperture of WKH$( )LQHO\ GLVSHUVHG DOXPLQRSKRVSKDWH FHPHQW $3& LWHP   EDVHGRQDOXPLQXPR[LGHLVDSSOLHGIRUULJLGIL[LQJRIWKHFRQGHQVHU sleeves in the near-electrode ceramic pipes (item 6) on the surface of WKHLUPXWXDORYHUODS$3&ZDVGHYHORSHGLQWKHFHUDPLFGHSDUWPHQW of The Istok Co. specially for fastening together the metal and ceramic internal parts of electrovacuum devices with an interval of RSHUDWLQJ WHPSHUDWXUHV IURP ±ƒ& WR ƒ& The cathode material (item 8) was a metal-porous tungstenEDULXP:±%D FDWKRGHZLWKDQDFWLYHVXEVWDQFHRIWKHFRPSRVLWLRQ %D2ā$O223ā&D2ā6L22 (barium aluminosilicate) with a minimum work function (2 eV) developed at the cathode department of The ,VWRN &R > &K @ 7KH :±%D FDWKRGH LV XQKHDWHG DQG RSHUDWHV in the regime of auto-thermoemission. The cathode is structurally a ring (position 13 in Figs. 3.6 and 3.7) mounted in a molybdenum cylindrical holder (item 12) and pressed tightly from the side of the discharge channel by a ceramic tube (item 6). An enlarged image of

New Generation of Efficient Sealed-off Active Elements

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the new cathode and a fragment of its working surface is shown in Fig. 3.8 a. In this case, the position of the tube (item 6) relative to WKH KROGHU LWHP   LV IL[HG ZLWK WKH$3& LWHP   DSSOLHG WR LWV surface and into the technological holes in the holder. The cathode holder (item 12), to ensure a reliable electrical contact, is soldered at the end to the base of a cup of alloy 47HD (item 15 in Figs. 3.6 and 3.7) of the electrode assembly. At the base of the cup, annular grooves are made to improve the radial thermal isolation of the cathode assembly. The dimensions of the cathode ring for low-power $( PRGHOV RI WKH */ $ DQG */ % PRGHOV LV  î  î  PP WKH PDVV LV  J IRU WKH */ % */ ' DQG */,  î  î  PP DQG  J 2I WKLV PDVV DERXW ± LV WKH DFWLYH VXEVWDQFH ± EDULXP DOXPLQRVLOLFDWH ZKLFK LV LPSUHJQDWHG ZLWK D porous tungsten cathode substrate. The melting point of tungsten LV ƒ& 7KH ZRUN IXQFWLRQ RI WKH DFWLYH VXEVWDQFH LV DERXW  eV. The activity of the cathode during operation is ensured by the continuous formation of free barium due to the reduction of the DFWLYH VXEVWDQFH E\ WXQJVWHQ %D2  :  %D 3:2 6%D  2Q WKH inner surface of the cathode there is an annular groove with a width RI ± PP ZKLFK HQVXUHV ORFDO DQG VWDEOH EXUQLQJ RI D SXOVHG arc discharge in the regime of auto-thermoemission and, accordingly, stable parameters of the output radiation beam. A localized cathode spot of about 1 mm in size progressively moves along the perimeter of the groove as the barium is depleted. The moving speed of the VSRW DV VKRZQ E\ WKH ORQJ WHVWV RI WKH $( RI WKH */( LV QR PRUH WKDQ  PPK ZKLFK FRUUHVSRQGV WR D VHUYLFH OLIH RI WKH FDWKRGHRIDWOHDVWKJXDUDQWHHGRSHUDWLQJWLPHDWƒ&RQ AE). Traces of erosion and penetration of tungsten from intense ion bombardment are distinctly observed on the working surface of the cathode (Fig. 3.8 b and c). In the operating mode, the cathode at the discharge localization locations is brightly glowed and heated to a temperature close to the melting point of tungsten (Tm ƒ& ZKLFKLQGLFDWHVLWVHIIHFWLYH operation in the auto-thermoemission regime. The anode is identical in design to the cathode, but is made of pure molybdenum. The anode LVVSUD\HGWRDPXFKOHVVHUH[WHQW7KHHURVLRQRIWKHDQRGHLVFDXVHG by the vibrational (damped) character of the development of the discharge and, accordingly, the anode work partially in the cathode mode, but at lower pulsed current values. At present, tungsten is also used as the anode material, the melting point of which is 1.3 times greater than that of molybdenum.

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7KH KHDW LQVXODWRU XVHG LQ VHOIKHDWLQJ$( LV D WKUHHOD\HU RQH ± KROORZ PLFURVSKHUHV RI7 EUDQG LWHP  LQ )LJ   RI $O 22 3 6L22 composition with operating temperature (Toper ƒ&DQG kaolin ILEHU 9.9 SRVLWLRQ   RI ±$O 22 3  ± 6L2 2 with T oper  ƒ& SURGXFHG E\ 13. 7HUP 0RVFRZ=HOHQRJUDG  DQG D ILEURXV PDWHULDO RI WKH W\SH 3\URILEHU  LWHP   RI  Al 2 2 3     6L2 2 with T oper   ƒ& IURP 'LGLHU *HUPDQ\  The advantage of a three-layer thermal insulator is a low thermal FRQGXFWLYLW\Ȝ DWKLJKRSHUDWLQJWHPSHUDWXUHVDQGDVPDOOVSHFLILF weight (ȡ), which leads to a decrease in the power consumption and heat capacity of the AE and, as a result, to an increase in efficiency and a decrease in the laser readiness time. The coefficient of thermal conductivity and specific gravity of the heat-insulating layer made RIWKH7PDWHULDOZLWKVL]HVRIWKHIUDFWLRQVRI±ȝPLWHP  immediately adjacent to the ‘hot’ discharge channel (position 1), are Ȝ :Pā. DQGȡ JFP2, the heat of the insulator from the material of grade VKV-1 (item 15), adjacent to the vacuum-tight VKHOO LWHP   Ȝ  :Pā.  DQG ȡ   JFP 2 DQG 3\URILEHU  LQVXODWRU LWHP   ZKLFK NHHSV WKH PLFURVSKHUHV PRYLQJ along the outer surface of the discharge channel to its ends and their VSLOOLQJ WKURXJK WKH KROHV LQ WKH FRQGHQVDWH 2UDFK LWHP  LQ )LJ  LQWKHZRUNLQJYROXPHRIWKHFKDQQHO±Ȝ :Pā. DQG ȡ   JFP 2. These heat insulators, prior to laying in the AE, for preliminary cleaning, are annealed in a high-temperature furnace (up to operating temperatures). The diameter of the separation boundary between the layers of thermal insulators of the T brand (item 13) DQG WKH 9.9 LWHP   LQ ORZSRZHU $( PRGHOV RI WKH */ $ DQG */% PRGHOVLVPPWKHPRGHOV*/9*/' DQG */, ±  PP WKH WHPSHUDWXUH LQ WKLV ]RQH LV QRW KLJKHU WKDQ ƒ& 7KH WKHUPDO LQVXODWRU 9.9 LV VLQWHUHG DW KLJKHU temperatures and its thermophysical properties deteriorate. The near-electrode regions of the AE, where the temperature is less than ƒ&DUHILOOHGZLWKDILEURXVKHDWLQVXODWRU9.9ZKLFKDORQJ the discharge channel is separated from the loose hollow microcircuit RI WKH KHDW LQVXODWRU 7 E\ WKH OD\HU RI WKH 3\URILEHU  ILEURXV KHDWLQVXODWRUZLWKWKHRSHUDWLQJWHPSHUDWXUHXSWRƒ&7KHUPDO LQVXODWRU 3\URILEHU  ZDV QRW XVHG LQ WKH ILUVW LQGXVWULDO VHOI heating AEs. The new heat insulator is located in the zone where WKH WHPSHUDWXUH RI WKH GLVFKDUJH FKDQQHO YDULHV IURP DERXW  WR ƒ&7KHUHIRUH LW GRHV QRW FDNH DQG FRQVHTXHQWO\ D JDS DORQJ the discharge channel is not formed and the heat insulator from the

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microspheres does not pour through the condenser holes into the channel volume, does not overlap its aperture and does not dust out the output windows. In the first (old) AE models the condenser zone contained the fibrous material BKV-1, which, due to the relatively ORZ RSHUDWLQJ WHPSHUDWXUH QR PRUH WKDQ ƒ&  ZDV VLQWHUHG over time, which facilitated the entry of the heat insulator from the PLFURVSKHUHVLQWRWKHFKDQQHODQGWKHH[LWZLQGRZVUHVSHFWLYHO\WR a decrease in the power and quality of the radiation. Thus, the threecomponent combination of the heat insulator in terms of its physicochemical properties and the thermal protection of the discharge channel fully meets the requirements for self-heating AE. The vacuum-tight shell of the AE, which also determines its appearance, includes three assemblies interconnected through metal FXSV E\ DUJRQDUF ZHOGLQJ 7KHVH LQFOXGH WKH PHWDO±JODVV VKHDWK LWHP WKHHOHFWURGHDVVHPEOLHVZLWKDFXSLWHP DQGDJODVV LWHP   DQG HQG VHFWLRQV LWHP   ,Q WKH ILUVW LQGXVWULDO QXFOHDU SRZHU SODQWV RI WKH W\SH */ 8/ 8/ DQG */ DV ZHOODVLQWKHQHZPRGHOV*/$DQG*/*WKHFDVLQJLWHP 16) had a cermet structure with increased mechanical strength. It consists of one or three ceramic cylinders made of 22KhS material $O223) and two metal cups at the ends of alloy 47ND, joined together by copper brazing. Soldering the parts into a single unit is GRQH LQ D K\GURJHQ IXUQDFH DW D WHPSHUDWXUH RI DERXW ƒ& 7KH disadvantages of the cermet structure include high weight, high cost, the emergence during the cyclical operation of microleaks in the SODFHV RI VROGHULQJ WKH SDUWV DQG XQILW IRU UHSHDWHG XVH7KH PHWDO± JODVVFRQVWUXFWLRQGRHVQRWKDYHWKHVHGUDZEDFNVDQGDVH[SHULHQFH VKRZV FDQ EH UHXVHG XS WR WKUHH WLPHV 7KH PHWDO±JODVV FDVLQJ (item 16) is a glass cylinder of the C52-1 grade with a diameter RI  PP IRU */& ' DQG ,  RU  PP IRU */%  WR WKH HQGV RI ZKLFK FXSV RI DOOR\ 1. .RYDU  DUH VROGHUHG E\ PHDQV RIDKLJKIUHTXHQF\JODVVJHQHUDWRULWHP 7RUHOLHYHVWUHVVHVLQ the soldering zone, the unit is annealed in a muffle furnace at T   “  ƒ& $ FXS LWHP   DQG D JODVV LWHP   IURP D QRQ deficient 47ND alloy are welded into a single electrode assembly with a copper solder form a vacuum-tight section connecting the VKHDWK LWHP   WR WKH HQG VHFWLRQ LWHP   7KHHQGVHFWLRQLWHP FRQVLVWVRIDJODVVF\OLQGHU&ZLWKD GLDPHWHURIPPRQHHQGRIZKLFKLVVROGHUHGE\DKLJKIUHTXHQF\ JHQHUDWRUZLWKDPHWDOEHDNHUPDGHRIDOOR\1.LWHP DQGWR WKH RWKHU ± E\ WKH IODPH RI D JDV EXUQHU WKH RSWLFDO ZLQGRZ LWHP

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  IURP$ JODVV &20  >@ ZLWK SDUDOOHOLVP RI SODQHV QR PRUH WKDQ Ǝ 7KH ILQLVKHG XQLW LV DQQHDOHG LQ WKH IXUQDFH DW T  “ ƒ& XQWLO WKH VWUHVVHV DULVLQJ DW LWV PDQXIDFWXUH DUH completely removed. The glass cylinder has a corrugated structure VHHLWHP ZLWKDQLQWHUQDOGLDPHWHUHTXDOWRWKHGLDPHWHURIWKH output radiation beam. This design allows to reduce the dusting of optical windows. (This technical solution is protected by patent No.    5) µ$FWLYH HOHPHQW RI D FKHPLFDO YDSRXU ODVHU¶ >@  The corrugated structure is one or several constrictions separated by reservoirs and operates as follows. Hot convective flows of a buffer gas of neon contaminated with vapours of the working substance and the products of erosion of the cathode and anode emerging from the discharge channel on the path to the optical window pass through a series of reservoirs. As a result of convection, gas circulation occurs in each of them, which causes a predominant deviation of WKH FRQWDPLQDWHG IORZ IURP WKH D[LDO GLUHFWLRQ YHUWLFDOO\ XSZDUGV The circulation of gas in a relatively narrow gap along the relatively cold walls of the reservoir leads to the condensation of particles on their surfaces. The lower the wall temperature, the more actively the condensation process proceeds. Moreover, the high activity of natural cooling of the walls of the reservoir is ensured by the development of their cooling surface. The relatively small thickness of the glass F\OLQGHU ZDOOV ± PP  SURPRWHV JRRG KHDW H[FKDQJH EHWZHHQ the heated gas and the surrounding medium, as well as an increase in thermal resistance along the frame of the corrugated element. The latter allows reservoirs to reduce the flow of heat from heated electrode assemblies and thereby reduce their temperature for a given area of the cooled surface. To eliminate in the AE an inverse parasitic connection with the active medium (AM), which arises from the reflected radiation from the output windows (item 21), the windows are located at an DQJOH WR WKH RSWLFDO D[LV RI WKH$(7KH HIIHFW RI LQFLGHQW UHIOHFWHG UDGLDWLRQLQWKH$0LVWKHGLVWRUWLRQRIWKHVSDWLDO±WLPHVWUXFWXUHRI the output radiation beam, that is, the deterioration of its quality. The PD[LPXPDOORZDEOHDQJOHRIWKHZLQGRZLVGHWHUPLQHGE\WKHHGJH beams of the beam of superradiance formed by the aperture of the discharge channel. From the consideration of the geometric variation of aperture rays propagating at an angle Dk/lk, it was established that in order to completely eliminate the parasitic coupling, the angle of LQFOLQDWLRQ RI WKH ZLQGRZ WR WKH RSWLFDO D[LV RI WKH$( VKRXOG QRW H[FHHG WKH YDOXH GHWHUPLQHG IURP IRUPXOD  

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7KLV WHFKQLFDO VROXWLRQ LV SURWHFWHG E\ WKH FHUWLILFDWH 1R  5) µ3XOVHG PHWDO YDSRXU ODVHU¶ >@ 7KH FDOFXODWHG YDOXHV RI WKH VORSH RI WKH ZLQGRZ IRU WKH $( VHULHV .XORQ */  DUH LQ WKH UDQJH Į  ±ƒ ,Q UHDO GHYLFHV LQ RUGHU WR FUHDWH D FRQVWUXFWLYH reserve, the angle of the window is reduced by several degrees. ,QVLGH WKH HQG VHFWLRQV LWHP   PHWDO EODFNHQHG VFUHHQ±WUDSV (item 22) of an ink-well construction with a continuous aperture close WRWKHGLDPHWHURIWKHUDGLDWLRQEHDPDUHFRD[LDOO\LQVWDOOHG7KHWUDS screens, like the corrugated structure of glass sections, are designed to protect the inner surface of optical windows from dusting with erosion products of electrodes, copper vapour and other substances formed during training and operating AE. The dusting of the windows leads to a decrease in power and a decrease in the degree of spatial coherence of the radiation. In order to increase the service life, efficiency, power and stability of the output parameters of the sealed-off CVL, a three-stage training technology for degassing and cleaning AE with a total duration RI ± K ZDV GHYHORSHG 7KLV WHFKQRORJ\ DOORZV SUHVHUYLQJ WKH purity of the gaseous medium in the AE until the end of its operation PRUH WKDQ  K $W WKH ILUVW VWDJH RI WKH$( WUDLQLQJ D KRXU degassing operation is performed at the pumping station when the WHPSHUDWXUH LV UDLVHG WR ƒ& WKH RXWSXW ZLQGRZV DUH ZHOGHG LQ the flame of the gas burner) and a 2 h holding at this temperature SRLQW7KH$(LVSXPSHGWKURXJKWKHJODVVH[KDXVWWXEHVLWHP  VROGHUHGWRWKHHQGVHFWLRQVLWHP WRDSUHVVXUHRI 5± 6 mm Hg. At the second stage of training, the AE is degassed in its own pulsed arc discharge with continuous pumping of buffer gas through it (at first cheap argon, and at the end the working neon) at the training and AE testing stands. To increase the temperature of the outer vacuum-tight shell of the AE there is a cylindrical aluminum screen around it, which also performs the function of the reverse current conductor. The latter leads to a decrease in the inductance of the discharge circuit of the power source and, correspondingly, to an LPSURYHPHQW LQ WKH FRQGLWLRQV IRU WKH H[FLWDWLRQ RI WKH$0 DQG WR an increase in the optimum operating temperature of the discharge channel of the AE. At this stage, due to a gradual increase in the power input from the power source to the AE, the temperature of WKH GLVFKDUJH FKDQQHO ULVHV IURP URRP WHPSHUDWXUH WR ƒ& WKH YDFXXPWLJKW VKHOO WR ƒ& H[FHHGLQJ WKH RSHUDWLQJ YDOXHV E\ DERXW ƒ& %XIIHU JDVHV DUJRQ DQG QHRQ DUH RI KLJK SXULW\ DQG DUH VWRUHG LQ  OLWHU PHWDO F\OLQGHUV DW D SUHVVXUH RI  NJFP 2

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DWP 7KH SXULW\ RI JDVHRXV DUJRQ LV QRW OHVV WKDQ  RI WKH YROXPHIUDFWLRQ78 QHRQ±QRWOHVVWKDQ78    $ SXUH JDV LV LQWURGXFHG LQWR WKH$( WKURXJK D JODVV H[KDXVW WXEH IURP WKH VLGH RI WKH FDWKRGH LWHP   DQG WKH HYDFXDWLRQ RI WKH µGLUW\¶ JDV LV YLD WKH H[KDXVW WXEH SRVLWLRQ   IURP WKH VLGH RI WKH DQRGH LWHP   7KH SURFHVV RI GHJDVVLQJ WKH AE is completed when the evacuated neon gas at the outlet (from WKH VLGH RI WKH DQRGH  ZKHQ H[FLWHG E\ D KLJKIUHTXHQF\ GHYLFH RI the Teslo type has the same bright red glow as the pure neon at the input. Depending on the AE model, the degassing time in the second stage of the training, i.e., in the discharge with the pumping of the EXIIHU JDV LV ZLWKLQ ± K ,Q WKH WKLUG VWDJH RI WKH WUDLQLQJ LQ RUGHU WR DFKLHYH PD[LPXP$( HIILFLHQF\ WKH VXUIDFH RI WKH FRSSHU vapour generators (item 4) and other elements from the two-stage is FOHDQHG IURP WKH UHIUDFWRU\ R[LGHV IRUPHG GXULQJ WKH SURFHVV )RU this purpose, gaseous hydrogen of spectral purity (H 2±E\ YROXPH78± WRDSDUWLDOSUHVVXUHRIPP Hg is introduced into the AE with neon at the operating temperature RIWKHGLVFKDUJHFKDQQHORIDERXWƒ&$IWHUQRWOHVVWKDQKDOIDQ hour, the neon is pumped through the AE until the ‘contaminated’ gas PL[WXUHLVFRPSOHWHO\SXULILHG7KHSURFHVVRIK\GURJHQSXULILFDWLRQ is repeated until the generators are completely wetted (spreading) by molten copper over the surface of the molybdenum substrate, DQG WKH UDGLDWLRQ SRZHU GRHV QRW UHDFK LWV PD[LPXP YDOXH DQG DFFRUGLQJO\ HYDSRUDWLRQ RI FRSSHU YDSRXU ± PD[LPXP UDWH $IWHU this technological operation, the device is filled with pure neon to the UHTXLUHG RSHUDWLQJ SUHVVXUH DQG VROGHUHG WKURXJK WKH JODVV H[KDXVW tubes (item 23). 3UHVHUYDWLRQ RI WKH SXULW\ RI WKH JDVHRXV PHGLXP LQ VHDOHG VHOI heating AEs and their relatively high power, as shown by long-term WHVWV DQG RSHUDWLRQ RI VHDOHGRII $(V RI WKH */& DQG */ '±K W\SHVLQWHFKQRORJLFDODQGPHGLFDOHTXLSPHQW attest to the high efficiency of the developed three-stage technology training on degassing and cleaning instruments. In studies with JDVHRXVK\GURJHQLWZDVIRXQGWKDWWKHDGGLWLRQRI±PP+JSXUH hydrogen in the AE, after the purification step, leads to an additional increase in efficiency and radiation power. Therefore, in order to maintain the radiation power of sealed self-heating AEs at a high level, hydrogen is added to a certain partial pressure before they are sealed-off before the gas is decanted into the buffer gas. Increasing the efficiency of CVL, which occurs when hydrogen is added, many

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DXWKRUVH[SODLQE\WKHLQWHQVLYHGHFUHDVHLQWKHHOHFWURQWHPSHUDWXUH in the afterglow period due to elastic and inelastic collisions with K\GURJHQ DWRPV DQG PROHFXOHV >@ The design, technology of manufacturing and training of AE of the Kristall series with a power of 30-100 W. Development of industrial sealed-off self-heating AEs of the Kristall series of the SXOVHG &9/ */ DFFRUGLQJ WR 78  ZDV FDUULHG RXW LQ SDUDOOHO ZLWKWKHGHYHORSPHQWRIWKH$(VHULHV.XORQ*/DFFRUGLQJWR 78 >@7KHEDVLFPDWHULDOVXVHGLQWKHVH$(VWKHGHVLJQ and manufacturing technology of the main units, and the technology for degassing the instruments are largely identical. The AE of he .ULVWDOO VHULHV KDV VHYHUDO WLPHV WKH OHQJWK ± ± P ZHLJKW ± ±NJVHH7DEOHVDQG DQGWKHSRZHUFRQVXPSWLRQ±± N:VHH7DEOHVDQG ZKLFKLPSRVHVDGGLWLRQDOUHTXLUHPHQWV on their design, manufacturing technology and training. As a part of the technological equipment the AEs of the Kristall series are usually operated in cylindrical water-cooled metal heat sinks with D IORZ UDWH RI DW OHDVW ± OPLQ 7KH KHDW VLQN DOVR SHUIRUPV WKH function of a reverse current lead, which leads to a decrease in the inductance of the discharge circuit and, accordingly, to an increase in the steepness of the front of the pump current pulses. AEs of the Kristall models GL-205A (30 W) and GL-205B (40W). Designs of industrial sealed-off self-heating AEs Kristall RQ FRSSHU YDSRXU PRGHO */$ ZLWK DQ DYHUDJH RXWSXW SRZHU RI : RSHQ QDPH .ULVWDOO /7&X  DQG */% ZLWK D SRZHU RI  : .ULVWDOO /7&X  DUH DOPRVW LGHQWLFDO 7KH GLDPHWHU RI WKH GLVFKDUJH FKDQQHO RI WKHVH $(V LV  PP 7DEOH   7KH $( */% LV  FP ORQJHU WKDQ WKH */$ $(  DQG  PP UHVSHFWLYHO\  DQG KDV VL[ FRSSHU YDSRXU JHQHUDWRUV ZKLFK LV WZR PRUH JHQHUDWRUV 7KH$( */$ LV D PRGHUQL]HG YDULDQW RI $( */ >@ */% ± PRGHUQL]HG YDULDQW RI $( */' >@EXWWKHOHQJWKRIWKHGLVFKDUJHFKDQQHODQGRYHUDOOGLPHQVLRQV GLG QRW FKDQJH GLDPHWHU  î  PP IRU $( */$ DQG GLDPHWHU  î  PP IRU WKH $( */%  7KH RXWHU SDUW RI the AE design is a cylindrical cermet shell (item 16) with electrode DVVHPEOLHVLWHP ZKLFKDUHVROGHUHGZLWKPHWDOOREHVLWHP  for connection to a high-voltage impulse power source, and end glass VHFWLRQV LWHP   ZLWK RSWLFDO ZLQGRZV LWHP   IRU WKH RXWSXW RI ODVHU UDGLDWLRQ )LJ   The discharge channel (item 1) of the AE of the Kristall series, like the AE of the Kulon series, is partitioned, consists of ceramic

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tubes (item 2), connected by ceramic bushings (item 3). Ceramics $ ZLWK WKH $O 2  2 3  R[LGH FRQWHQW RI  ZDV XVHG ,Q WKH junction points of the channel sections, that is, in the blind grooves, copper vapour generators are located (item 4). The design of the sectionalized discharge channel is protected by two RF patents: IRU LQYHQWLRQ 1R    >@ DQG D XWLOLW\ PRGHO 1R  >@$WXQJVWHQ±EDULXPFDWKRGHLWHP SURYLGHVDKLJKGHJUHHRI localization and stability of burning of a pulsed arc discharge. Inside WKH HQG VHFWLRQV LWHP   WUDS VFUHHQV LWHP   DUH LQVWDOOHG WR SURWHFW WKH H[LW ZLQGRZV IURP FRSSHU YDSRXU DQG RWKHU VXEVWDQFHV and sputtering products of the cathode and anode. The threelayer heat insulator (positions 13, 14 and 15), located between the discharge channel (item 1) and the vacuum-tight shell (item 16), provides the required operating temperature of the discharge channel XS WR ƒ&  DW UHODWLYHO\ ORZ SRZHU FRQVXPSWLRQV +LJKSXULW\ QHRQ LV XVHG ± QRW OHVV WKDQ  DV D EXIIHU JDV LQ ZKLFK D pulsed discharge burns, . 7KH GLVFKDUJH FKDQQHO RI WKH$( */$ LWHP  LQ )LJ   consists of three central ceramic tubes with a length of 186 mm (item 2) and two near-electrode slotted ceramic tubes of 123 mm length SRVLWLRQ ZLWKDQLQWHUQDOGLDPHWHURIPPDQGDZDOOWKLFNQHVV RI  PP 7KH GLVFKDUJH FKDQQHO RI WKH HORQJDWHG $( */% uses five central ceramic tubes (item 2), each of which has a length of 165.5 mm. The central tubes of the channel are connected with HDFK RWKHU E\ FHUDPLF EXVKLQJV LWHP   ZLWK D OHQJWK RI  PP

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ZLWKHOHFWURGHWXEHVPPORQJ7KHLQQHUVXUIDFHRIWKHFRQQHFWLQJ bushings is ground and has a fitting diameter 25.7 mm. The thickness of the walls of the sleeves is 2.65 mm, the length of their mutual overlapping with the tubes is 15 mm. In the old (basic) AE models */DQG*/'WRFRQQHFWWKHWXEHVWRWKHVOHHYHVWKHHQGV of the ceramic tubes were ground over the outer surface by a length RI  PP DQG KDG DQQXODU SURMHFWLRQV IRU IL[LQJ WKH EXVKHV ZKLFK turned out to be concentrators of mechanical stresses. The latter often led to the destruction of the discharge channel. Therefore, in the new PRGHOV RI WKH $( */$ DQG */% WKH GLVFKDUJH FKDQQHO WXEHV ZHUH PDGH HLWKHU ZLWK PLQLPDO IL[LQJ SURWUXVLRQV )LJ   RU VPRRWK DORQJ WKH HQWLUH OHQJWK )LJ   Assembling the discharge channel with a smooth tube surface )LJ   GLIIHUV IURP WKH DVVHPEO\ RI WKH ROG GHVLJQ DQG LQFOXGHV the following technological operations. First, a high-temperature VHDOLQJILQHFHPHQWRIWKHFRPSRVLWLRQ±$O 22 3±7L2 2 (item 12) is applied to the length of 15 mm from the ends of the WXEHV DORQJ WKH H[WHUQDO VXUIDFH 7KH ZRUNLQJ WHPSHUDWXUH RI WKH FHPHQW LV ƒ& LWHP   Then these tubes (item 2) are serially connected by ceramic bushings (item 3), with copper vapour generators installed in them (item 4). 7KHVOHHYHVUHODWLYHWRWKHWXEHVDUHVXFFHVVLYHO\IL[HGZLWKVSHFLDO PDQGUHOV $IWHU WKH FHPHQW ELQGHU KDV GULHG WKH IL[LQJ PDQGUHOV from the discharge channel are removed. In the process of training AE before T chan   ±ƒ& WKH FHPHQW LV VLQWHUHG DQG WKH channel design becomes sealed and rigid. The lifetime of an AE

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with a sealed discharge channel is determined practically only by the diffusion of copper vapour along the discharge channel (position 1) to its relatively cold ends. In the end electrode tubes (position 5) of WKHGLVFKDUJHFKDQQHOWKHUHDUHORQJLWXGLQDOVORWWHGKROHVRIVL]H î  PP )LJ   GHVLJQHG WR GLVFKDUJH FRSSHU YDSRXU LQWR KHDW insulators (items 13, 14 and 15), where they condense. (The design is protected by copyright certificate No. 1 572 367 of the USSR µ$FWLYH HOHPHQW RI D FKHPLFDO YDSRXU ODVHU¶ >@ ,Q WKH ROG GHVLJQ RI WKH GLVFKDUJH FKDQQHO $( */ DQG */ ' WKHIXQFWLRQRIHDFKVOLWFHUDPLFWXEHZDVSHUIRUPHGE\WKUHH parts: an electrode ceramic sleeve, an end tube of the channel and a cylindrical molybdenum tube with slots connecting a ceramic tube and a sleeve. The molybdenum tube limited the life of the AE, since when it is used for a long time in high-temperature conditions, it becomes brittle and collapses in a cyclic mode of operation. 7KH DFWLYH VXEVWDQFH YDSRXU JHQHUDWRUV LWHP  LQ )LJ   ZLWK D F\OLQGULFDO PRO\EGHQXP VXEVWUDWH LWHP  LQ )LJ   ZKLFK are the most efficient sources of copper vapour, are placed between ceramic tubes on the inner surface of the connecting sleeves (item 3), i.e., in the blind grooves of the discharge channel. In order not to deform the molybdenum substrate, the substrate has openings for free passage of molten copper from the surface of the substrate to the gap with the ceramic sleeve and vice versa (Fig. 3.12). (This generator GHVLJQ LV SURWHFWHG E\ D SDWHQW IRU XWLOLW\ PRGHO 1R  >@ 7KURXJK WKH KROHV WKH H[FHVV PHWDO ZLOO EH IRUFHG RXW QRW mainly into the ceramic tubes of the discharge channel, but to the surface of the molybdenum substrate, where it is spread out without IRUPLQJ FRQYH[ GURSOHWV DQG QRW RYHUODSSLQJ WKH DSHUWXUH RI WKH AE channel. At the same time, the dimensions of the gaps should

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be such that the elements of the unit structure do not collapse when the channel is heated. This requirement is ensured by the fulfillment of two conditions. The first condition is that the radial dimension of the molybdenum cylindrical substrate is smaller than WKHJURRYHVL]HLQQHUUDGLXVRIWKHFHUDPLFVOHHYH E\WKHYDOXHǻR  R·T î k 2  í K 1 )/(1 + k 2 ·T  WKH VHFRQG LV WKH D[LDO GLPHQVLRQ RI WKH VXEVWUDWH OHVV WKDQ WKH D[LDO GLPHQVLRQ RI WKH JURRYH ǻH  H·T·(k 2ík 1)/(1 + k 2·T), where R and H are the radius and width of WKH JURRYH ZKHUH WKH FRSSHU YDSRXU JHQHUDWRUV >P@ DUH ORFDWHG T LV WKH RSHUDWLQJ WHPSHUDWXUH RI WKH GLVFKDUJH FKDQQHO >ƒ&@ k 1 and k 2DUHWKHFRHIILFLHQWVRIWKHUPDOH[SDQVLRQRIWKHVXEVWUDWHDQGWKH material of the elements forming the grooves [degí@7KHSHUIRUDWLRQ of the substrate and the presence of gaps in the grooves have made it possible to increase the overall reliability of copper vapour generators and adjacent nodes. In the design of the discharge channel, the width of the groove GLVWDQFH  EHWZHHQ WKH FHQWUDO FHUDPLF WXEHV RI WKH FKDQQHO LV  PPEHWZHHQWKHRXWHUFHQWUDODQGQHDUHOHFWURGHVOLWWXEHV±PP According to the above formulas, at the working temperature of the discharge channel T  ƒ& DQG WKH FRHIILFLHQWV RI WHPSHUDWXUH H[SDQVLRQRIWKHPDWHULDOVk 1 ā ± deg í and k 2 ā í deg í UDGLDO DQG WKH D[LDO FOHDUDQFHV VKRXOG QRW EH OHVV WKDQ ǻR  ȝPǻH  ȝPDQGǻH  ȝP7KHVHJDSVZLWKDPDUJLQ were taken into account in the allowances for responsible details. 7KHPDVVRIFRSSHULQWKHFHQWUDOJHQHUDWRUVLVJLQWKHH[WUHPH JHQHUDWRUV±J6LQFHWKHH[WUHPHJHQHUDWRUVDUHORFDWHGFORVHU to the gap openings of the electrode tubes, the consumption of copper in them is larger and it is necessary to lay more copper in them (see formula 3.2)). In the operating mode, the relative thermal elongation of WKH GLVFKDUJH FKDQQHO RI WKH $( */$ LV DERXW  PP $(

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*/% ±  PP T a ƒ& WKHUPDO H[SDQVLRQ FRHIILFLHQW D 7$O223 ā7 . 1 ). Therefore, the structural elements of the AE electrode assemblies should not interfere with the free movement of WKH GLVFKDUJH FKDQQHO DORQJ WKH D[LV GXULQJ LWV WKHUPDO HORQJDWLRQ DQG FRROLQJ ,Q WKH ROG $( */ XQGHU WKH WKHUPDO HORQJDWLRQ of the channel, the thin-walled bases of the cups of electrode assemblies with radial grooves played the membrane function; in WKHHORQJDWHG$(*/(DVWDLQOHVVVWHHOEHOORZVLQVWDOOHGLQWKH DQRGH DVVHPEO\ ,Q WKH QHZ PRGHOV RI$( */$ DQG */% the electrode assemblies are structurally made without membranes and bellows. This construction is simple, and no stress arises when WKH GLVFKDUJH FKDQQHO LV H[SDQGHG LQ LW ,Q WKLV FDVH WKH FDWKRGH LWHPLQ)LJ DQGWKHDQRGHLWHP XQLWVDUHLQVWDOOHGGLUHFWO\ on the ends of the electrode ceramic tubes (item 5) and connected to WKHHOHFWURGHFXS E\IOH[LEOHFXUUHQWFDUU\LQJVWULSVLQWKHIRUP of a loop (item 25). The material of the loop is nickel, aluminium RU FRSSHU VWULS ± PP WKLFN 7KH GHVLJQ RI WKH QHZ HOHFWURGH DVVHPEO\ LV SURWHFWHG E\ D SDWHQW IRU XWLOLW\ PRGHO 1R  5) $FWLYH HOHPHQW RI D PHWDO YDSRXU ODVHU >@ 7KH XQKHDWHG PHWDOSRURXV WXQJVWHQ±EDULXP FDWKRGH LWHP  LQ )LJ LVVWUXFWXUDOO\DULQJWKDWKDVEHHQUROOHGLQWRDPRO\EGHQXP cylindrical holder. The latter, to ensure a reliable electrical contact, is welded along the end to the molybdenum cylindrical cuff of the HOHFWURGH DVVHPEO\ 7KH VL]H RI WKH FDWKRGH ULQJ LV  î  î  PP DQG WKH PDVV LV  J 2I WKLV PDVV DSSUR[LPDWHO\   J  LV PDGH XS RI DQ DFWLYH VXEVWDQFH RI WKH FRPSRVLWLRQ %D2ā$O 22 3 î &D2ā6L2 2 (barium aluminosilicate), which impregnated the porous tungsten ring cathode substrate. The work function of the DFWLYH VXEVWDQFH LV DERXW  H9 2Q WKH LQQHU VXUIDFH RI WKH FDWKRGH WKHUHLVDQDQQXODUJURRYHZLWKDZLGWKRI±PPDQGDGHSWKRI up to 3 mm, which ensures local and stable burning of the pulsed DUF GLVFKDUJH 7KH DQQXODU :±%D FDWKRGH ZLWK DQ DQQXODU JURRYH on the inner working surface, rolled into a cylindrical molybdenum holder, is shown in Fig. 3.13. $VWKHEDULXPLVGHSOHWHGWKHORFDOL]HGFDWKRGHVSRWDERXW± mm in size gradually moves along the perimeter of the groove as the barium is depleted. The moving speed of the spot, as evidenced E\ WKH SURORQJHG WHVWV RI WKH$( LV a PPK WKDW LV WKH OLIH RI WKH FDWKRGH LQ WKH .ULVWDOO $( LV DERXW  KRXUV 7UDFHV RI erosion from intense ion bombardment are clearly observed on

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the cathode working surface. In this case, the tungsten substrate is partially sprayed. )LJXUHVKRZV:±%DFDWKRGHVLQPRO\EGHQXPKROGHUVVSHQW DERXW  KRXUV OHIW  DQG  KRXUV ULJKW  At the place of discharge localization, the cathode is heated up WR D EULJKW JORZ LH WKH XQKHDWHG :±%D FDWKRGH DV LQ WKH .XORQ AE series, operates in an auto-thermoemission regime. The anode of this construction is identical to the cathode and was made of molybdenum. It turned out that the molybdenum anode is partially atomized, but much less than the cathode. The erosion of the anode is caused by the vibrational (damped) character of the development of the discharge and, accordingly, by the anode work partially in the cathode mode, but at lower pulsed current values. At present, pressed tungsten, the melting point of which is 1.3 times greater than that of molybdenum, is used as an anode material. The tungsten anode is almost unaffected in the modes of pulsed CVL erosion. The three-layer effective thermal insulator of the AE (items 13 DQG  LQ )LJ   ORFDWHG EHWZHHQ WKH GLVFKDUJH FKDQQHO LWHP 1), and the vacuum jacket (item 16) provides thermal protection of WKH FKDQQHO ZLWK DQ RSHUDWLQJ WHPSHUDWXUH RI DERXW ƒ& 7KH inner layer (position 13) adjacent directly to the discharge channel is formed of a fine powder based on T-shaped hollow microspheres $O 22 3   6L2 2  DW DQ RSHUDWLQJ WHPSHUDWXUH RI ƒ& WKH WRSOD\HULWHP ±$O223±7L22) with the working WHPSHUDWXUHRIƒ&VHH7DEOH 7KHGLDPHWHURIWKHERXQGDU\ separating the layers of the heat insulator is 55 mm, the temperature LQWKLV]RQHLVQRWPRUHWKDQƒ&7KHQHDUHOHFWURGHUHJLRQVRI the AE are filled with the heat-insulator VKV-1, which is separated from the main two-layer heat insulator by a layer of a new fibrous KHDWLQVXODWRULWHP VXFKDV3\URILEHUE\'LGLHUFRPSDQ\  $O 22 3   6L2 2  DW DQ RSHUDWLQJ WHPSHUDWXUH RI ƒ& RU $OWUDPDW  ± ZLWK WKH VDPH RSHUDWLQJ WHPSHUDWXUH ,Q SUHYLRXV models, heat insulators of this quality were not used. A new heat insulator is located in the zone where the temperature of the channel YDULHV IURP DERXW  WR ƒ&7KHUHIRUH LW GRHV QRW FDNH DQG consequently, a gap along the discharge channel is not formed and the powder heat insulator do not escape through the slotted holes of the electrode tubes into the channel volume, does not block it DQG GRHV QRW SROOXWH WKH H[LW ZLQGRZV ,Q WKH ROG PRGHOV RI $( this zone contained the fibrous material VKV-1, which eventually sintered, which contributed to the ingress of powder into the channel

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through the cracks in the tubes. The sintering of the material also led to an increase in the non-uniformity of the temperature distribution DORQJ WKH D[LV RI WKH GLVFKDUJH FKDQQHO DQ LQFUHDVH LQ WKH SRZHU consumption and, accordingly, a decrease in the radiation power. New models of AE have practically no such drawbacks. They are also LQFUHDVHGE\DSSUR[LPDWHO\WLPHVERWKWKHGHQVLW\RIEDFNILOOLQJ of hollow microspheres, and the packing density of fibrous material VKV-1, which led to a decrease in the power consumption by about ±,IWKHPDVVRIWKHPLFURVSKHUHVDQGILEURXVPDWHULDOLQWKH */$(ZDVDQGNJWKHQLQWKH$/(*/$±DQG NJLQ*/(±DQGNJDQGLQ*/%±DQGNJ ,Q WKH $( */$ DQG */% WKH EURDGHQHG HQGV RI WKH cermet vacuum casing (item 16) were elongated in comparison with WKH ROG$(V */ DQG */( IURP  WR  PP )LJ  a and b). This led to an increase in the temperature of the ends of the discharge channel and, correspondingly, to an increase in the length of its active zone. The inner diameter of the ceramic cylinders .K6$O223 LQWKHVKHOOH[WHQVLRQVLVPPWKHWKLFNQHVV LVPPLQWKHFHQWUDOSDUWDQGPPUHVSHFWLYHO\6WUXFWXUDOO\ WKH */$ VKHOO )LJ  a) consists of four welded cermetal DVVHPEOLHV ZLWK PHWDO µWUD\V¶ ± PP WKLFN RI DOOR\ 1' RU 1. ZLWK FRPSHQVDWLQJ FHUDPLF ULQJV  PP LQ KHLJKW The nodes are interconnected by means of argon-arc welding of WKH HQG SODWHV 7KH OHQJWK RI WKH HQYHORSH RI WKH $/ */% LV  PP ODUJHU WKDQ WKDW RI WKH */$ GXH WR WKH DGGLWLRQ RI D single cermet assembly (Fig. 3.15 b). Today the industrial AE of the Kristall series is produced mainly with a metal-glass vacuum-tight shell (Fig. 3.16). 7KHPHWDOJOD]HGVKHOORIWKH$(*/$)LJD FRQVLVWV of two identical sections connected by argon-arc welding through WKH HQG WUD\V GLDP  PP  IURP WKH DOOR\ 1. .RYDU  7KH & JODVV F\OLQGHUV XVHG LQ WKH VHFWLRQV KDYH D GLDPHWHU RI 

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DQG  PP ,Q WKH HORQJDWHG$( */% WKH VKHOO )LJ  b) FRQVLVWV RI WKUHH VHFWLRQV WKH FHQWUDO DQG WZR LGHQWLFDO HQG :KHQ assembling the AE, the shell, also by means of argon-arc welding, is FRQQHFWHGWRWKHFXSV)LJLWHP RIWKHHOHFWURGHDVVHPEOLHV through the end plates, the latter with the kovar cups (pos.17) of the end glass sections. The metal-glass casing in the manufacture is more technologically and the yield coefficient of suitable products LV DOPRVW $W WKH VDPH WLPH WKH FRVW RI$( LV ± ORZHU than with the cermet shell. The most important for sealed AEs ZLWK PHWDO±JODVV FRQVWUXFWLRQ LV WKH IDFW WKDW LQ WKH FRXUVH RI WKHLU long-term operation there were practically no failures associated with violation of the vacuum density of the shell. In the case of a cermet structure, especially when operating in a cyclic mode, non-renewable failures occurred due to the depressurization of the FDVLQJ SUHIHUDEO\ DW WKH PHWDO±FHUDPLF MXQFWLRQ 8VXDOO\ DIWHU WKH end of operation, AEs are dismantled by nodes for the purpose of their evaluation for subsequent use in new devices. For this purpose, the outer shell of the EA is cut at the seams of argon-arc welding of metal ‘trays’ to the following sites: a vacuum-tight shell (item 16), WZR HOHFWURGH DVVHPEOLHV LWHP   DQG WZR HQG VHFWLRQV LWHP   :KHQ PHFKDQLFDOO\ VDZLQJ WKH FHUPHW VKHOO )LJXUH   XVXDOO\ EHFRPHVQRWVHDOHGDQGILUVWRIDOOWKHPHWDO±FHUDPLFMXQFWLRQVDQG the recovery for reuse are not subject. The vacuum density of the VKHOORIWKHPHWDO±JODVVVWUXFWXUHZKHQGLVDVVHPEOLQJWKH$(LVQRW violated. It is suitable for two-three times the repeated use, depending on the technological margin of the diameter of the welded end plates (diam. 134 mm in Fig. 3.17). This is another significant advantage IRU LQGXVWULDO$(V ZLWK WKH PHWDO±JODVV VKHDWK $ PHWDO±JODVV RU PHWDO±FHUDPLF VKHOO LWHP  LQ )LJ   HOHFWURGH DVVHPEOLHV LWHP   DQG HQG VHFWLRQV LWHP   interconnected at the ends by argon-arc welding, form a single

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outer vacuum-tight shell. The main element of the end sections is the optical window (item 21) for the output of laser radiation. At the first stage of the manufacturing process of the section, a glass F\OLQGHU ZLWK D GLDPHWHU RI  PP RI & JUDGH LWHP   LV VROGHUHGWR DJODVVRI1.DOOR\LWHP XVLQJDKLJKIUHTXHQF\ generator. To completely remove stresses in the soldering zone, the finished assembly is annealed at T   “  ƒ& IRU ± PLQ IRU H[DPSOH LQ D PXIIOH IXUQDFH$IWHU WKLV RSHUDWLRQ WKH IODPH RI a gas burner is used to produce a constriction (corrugation) with an internal diameter close to the diameter of the radiation beam in the glass cylinder, the end of the cylinder narrows to the fitting VL]H RI WKH H[LW ZLQGRZ DQG D JODVV H[KDXVW WXEH SRVLWLRQ   LV soldered for pumping and evacuation of gases during AE training VHH LWHPV   DQG   7KHQ WKH XQLW LV DQQHDOHG DJDLQ DW WKH same temperature and holding time and the end of the cylinder is JURXQG DW DQ DQJOH WR WKH RSWLFDO D[LV GHWHUPLQHG E\ IRUPXOD   7KHH[LWZLQGRZVDUHPDGHRI$&20 RSWLFDOJODVV>@ and have a diameter of 72 mm, a thickness of 7 mm and a deviation IURP WKH SDUDOOHOLVP RI WKHLU SODQHV RI QRW PRUH WKDQ ± WKH windows (item 21), using structural high-strength adhesive grade 063 ZLWK DQ RSHUDWLQJ WHPSHUDWXUH RI ƒ& GHYHORSHG E\ WKH ,VWRN &RPSDQ\ 78   ±  DUH JOXHG WR WKH HQG JODVV VHFWLRQV LWHP   7KH PD[LPXP WHPSHUDWXUH RI WKH RXWSXW windows during the operation of the AE in a closed cylindrical heat VLQNLV±ƒ&$WWKH$(WHVWVIRUPRUHWKDQKRXUVDERXW F\FOHVRIVZLWFKLQJRQDQGRII WKHGHSUHVVXUL]DWLRQRIWKHJOXHG nodes did not take place. This way of connecting the output windows to the end sections does not introduce deformations into the window material and leads to an improvement in the quality of the output

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UDGLDWLRQ EHDP ,Q WKH ROG PRGHOV */ DQG */' RSWLFDO windows were welded to the glass sections in the flame of the gas burner, which is why the quality of the output radiation has been GLVWRUWHG WR VRPH H[WHQW $W WKH VDPH WLPH WKH UHMHFWV DVVRFLDWHG with the deterioration of the quality of the window when welding, are LQ WKH UDQJH RI ± DQG GHSHQG RQ WKH LQGLYLGXDO TXDOLWLHV DQG TXDOLILFDWLRQVRIWKHJODVVEORZHU3URPLVLQJLVWKHXVHDVDPDWHULDO of the output windows of KV quartz instead of glass, which absorbs less heat from the heated discharge channel and does not lead to the occurrence of internal stresses. But this requires a new design of the HQG VHFWLRQ VLQFH WKH FRHIILFLHQW RI WKHUPDO H[SDQVLRQ RI JODVV DQG quartz differ by an order of magnitude. )RU WKH .ULVWDOO $( RI WKH PRGHO RI WKH */$ PRGHO WKH calculated value of the slope angle of the output window to the RSWLFDO D[LV RI WKH$( LQ DFFRUGDQFH ZLWK WKH IRUPXOD   >@ LVĮ ƒ*/%±Į ƒ,QUHDO.ULVWDOOGHYLFHVDVLQWKH previously reviewed Kulon systems, in order to create a constructive reserve, the angle of the window with respect to the calculated data ZDV UHGXFHG WR ƒ$W WKLV DQJOH WKH LQYHUVH SDUDVLWLF FRQQHFWLRQ ZLWK WKH DFWLYH PHGLXP LV FRPSOHWHO\ H[FOXGHG DQG WKHUH LV QR distortion of the spatiotemporal structure of the output radiation EHDP7RUHGXFHWKHUDGLDWLRQSRZHUORVVHVDWWKHH[LWZLQGRZVRI$( associated with Fresnel reflection (ȡ  WKHZLQGRZVXUIDFHVLQ the new models are enlightened. The enlightened film is resistant to ultraviolet radiation from the discharge plasma and the transmission FRHIILFLHQW UHPDLQV DW  IRU WKH HQWLUH OLIH RI WKH$( ,Q RUGHU WR HIIHFWLYHO\ SURWHFW WKH LQQHU VXUIDFH RI WKH H[LW windows from sputtering with the products of electrode erosion, active substance vapours and other particles during the training DQG RSHUDWLRQ RI WKH $( WUDS VFUHHQV LWHP  LQ )LJ   DQG constrictions (corrugations) are used in the end glass sections SRVLWLRQ   >@ 7KH LQWHUQDO GLDPHWHU RI WKH WUDS VFUHHQV DQG corrugations is equal to or close to the diameter of the radiation beam. In the upper part of the trap screens (item 22), on the side RI WKH JODVV H[KDXVW WXEHV SRVLWLRQ   WKHUH LV D VHULHV RI KROHV intended for free passage of the buffer gas in the pumping mode during the training of the AE. The technology of training and assembly of high-temperature self-heating AE on copper vapour has its own specific features DQG NQRZKRZ ZKLFK DUH QRW FRQVLGHUHG KHUH :H QRWH RQO\ D IHZ points. Training on the degassing of the AE of the Kristall model

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*/$ LV SHUIRUPHG E\ DQDORJ\ ZLWK WKH WKUHHVWDJH WUDLQLQJ UHJLPH RI WKH $( .XORQ DQG WKH WZRVWDJH EDVLF $( */ 7KH purpose of AE training is to achieve high and stable parameters of output radiation and to preserve them in the course of longterm operation by removing from the AE the impurity gases and vapours released from the elements of its design. At the first stage RI WUDLQLQJ WKH $( */$ IRU GHJDVVLQJ LWV  K HYDFXDWLRQ LV carried out with simultaneous heating in the furnace to a temperature RIƒ&OLPLWHGE\WKHRSHUDWLQJWHPSHUDWXUHRIWKHJOXH063  At the second stage of training, when AE is placed inside a thermal aluminum cylindrical screen, degassing is carried out in the burning mode of its own arc pulsed discharge with pumping argon and neon buffer gas from the cathode to the anode. The screen allows to raise WKH WHPSHUDWXUH RI WKH YDFXXPWLJKW VKHOO E\ ±ƒ& DERYH WKH operating temperature. In the third stage, the device is cleaned in a UHGXFLQJHQYLURQPHQW±LQDQDWPRVSKHUHRIPROHFXODUK\GURJHQ7R date, the technology of AE training without a pumping phase with KHDWLQJ LQ WKH IXUQDFH LV DYDLODEOH :LWKRXW WKLV VWDJH WKH GXUDWLRQ RI WKH $( */$ WUDLQLQJ LV DSSUR[LPDWHO\  KRXUV ZKLFK LV  WLPHV PRUH WKDQ IRU WKH EDVH */ 7KH ODWWHU LV GXH WR  times higher density of packing of the heat insulator and somewhat ODUJHU YROXPH 7KH WUDLQLQJ PRGH RI WKH$( */% LV VLPLODU WR WKH WUDLQLQJ PRGH RI */$ DQG WDNHV DERXW  KRXUV ZKLFK LV 1.33 times more.

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Design and manufacturing technology for industrial sealed-off self-heating AE Kristall model GL-205C (55 W). The industrial VHDOHGRII VHOIKHDWLQJ $( .ULVWDOO PRGHO */9 RSHQ QDPH ± .ULVWDOO /7&X  ZLWK DQ RXWSXW SRZHU RI ± : LV VKRZQ LQ Figs. 3.3 and 2.17. In Fig. 3.3 shows the appearance of AE with a FHUPHWVKHOOLQ)LJFRORULQVHUW ±ZLWKDPHWDOJODVVVKHDWK DQG LQ )LJ  ± LWV FRQVWUXFWLRQ $(*/9LVDPRGHUQL]HGYHUVLRQRIWKH$(*/'DQG has the same overall dimensions and length of the discharge channel DV WKH */% 7KH GLVFKDUJH FKDQQHO KDV D GLDPHWHU RI  PP DQGDOHQJWKRIPPWKHYROXPHRIWKHDFWLYHPHGLXPLVDERXW  FP 3. The mass of the AE is 15 kg (see Table 2.2). 7KH GLVFKDUJH FKDQQHO LWHP   $( */9 FRQVLVWV RI ILYH ceramic tubes (item 2), each 151 mm long and two 65 mm long, having an internal diameter of 32 mm and a wall thickness of 2.65 mm, and two near-electrode end) slotted tubes (item 5) with a length of 115 mm with an internal diameter of 37.3 mm and a wall thickness RIPP(LJKWORQJLWXGLQDOVORWVRIVL]HîPPDYDLODEOHLQWKH electrode tubes (item 5), are intended for the care of copper vapour into the heat insulator. The central tubes (item 2) of the discharge channel are connected with each other by four ceramic bushings LWHP   ZLWK D OHQJWK RI  PP DQG WKH HQG   E\ WZR OHQJWKV RI  PP ZLWK DQ LQWHUQDO GLDPHWHU RI  PP DQG D WKLFNQHVV RI 3 mm. The outer surface of the used ceramic tubes (item 2) of the FKDQQHO LV VPRRWK LH ZLWKRXW DQQXODU VWHSV DW WKH HQGV IRU IL[LQJ WKHFRQQHFWLQJVOHHYHVLWHP 6WHSVDVVKRZQE\WKHH[SHULHQFHRI AE operation in a cyclic mode, lead to the appearance of ring cracks in thick-walled tubes and, as a consequence, to the destruction of the discharge channel due to the occurrence of mechanical stresses. Therefore, when assembling (practically gluing) the discharge FKDQQHOWKHIL[DWLRQRIWKHWXEHVDQGFRQQHFWLQJVOHHYHVZLWKUHVSHFW to each other is carried out using special mandrels. The design of the sectionalized discharge channel is protected by two RF patents: for LQYHQWLRQ 1R    >@ DQG XWLOLW\ PRGHO 1R  >@ The construction and technology of manufacturing the discharge channel (item 1, figure 3.18), copper vapour generators (item 4), FDWKRGHLWHP DQGDQRGHLWHP HOHFWURGHDVVHPEOLHVLWHP  electrode tubes ( 5) heat insulators (item 12, 13, 14), vacuum-tight shell (item 16), output optical windows (item 21), end sections (item  DQGWUDSVFUHHQVLWHP $(*/9DUHVLPLODUWRWKRVHXVHG

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LQ*/$DQG*/%(OHPHQWVRIWKHFRSSHUYDSRXUJHQHUDWRU LWHP   DUH VHSDUDWHO\ VKRZQ LQ )LJ  DQG  7KH EH]QDNDOQ\ WXQJVWHQEDULXP ULQJ FDWKRGH$( */9 VL]H îîPPZLWKDQLQQHUDQQXODUJURRYHPPZLGHLWHP  LQ )LJXUH   FRQWDLQLQJ DERXW  RI WKH PDVV RI WKH DFWLYH substance of barium aluminosilicate, as well as in other models of AE Kristall, provides a stable local combustion of the pulsed arc discharge during the entire service life. In Fig. 3.21 (color insert) VKRZV QHZ DQG SDUWLDOO\ XVHG FDWKRGHV RI $( */9 VHH DOVR Figs. 3.8, 3.13 and 3.14). A vacuum-tight cermet shell with an outside diameter of the ceramic cylinder of 114 mm and a wall thickness of 5 mm (Fig. 3.22 a) has no broadening at the ends, as ceramic cylinders made of 22KhS material with a large diameter are not produced by the Istok company. At the same time, the length of the core of the */& $( UHODWLYH WR WKH */% ZKLFK KDV WKH VDPH OHQJWK of the discharge channel, decreases somewhat due to a smaller layer of thermal insulation at the ends of the channel. Therefore, in order to increase the temperature at the ends of the discharge channel, the packing density of the fibrous heat insulator of grade VKV-1 along the ends of the shell was increased in comparison with the central SDUW&XUUHQWO\LQGXVWULDOVROGHUHG$(V*/&DUHSURGXFHGRQO\

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EUDQG ZLWK D GLDPHWHU RI  PP DQG D ZDOO WKLFNQHVV RI  PP WR WKHHQGVRIZKLFKWKHJODVVHVDUHVROGHUHGIURP1.DOOR\NRYDU  7KHWUDLQLQJPRGHIRULQGXVWULDOVHDOHGVHOIKHDWLQJ$(*/9IRU degassing and its purification is similar to the three-stage training UHJLPH IRU LQGXVWULDO $( */% 7KH WRWDO GXUDWLRQ RI WUDLQLQJ $( */& LV OLNH WKH */% DERXW  KRXUV DV WKH PDVVHV RIWKHLUWKHUPDOLQVXODWRUVDUHDSSUR[LPDWHO\HTXDO7KHDQDO\VLVRI ± K RI RSHUDWRQ RI WKH VHDOHGRII$( */& ZKHQ WKH operating temperature of its discharge channel under the conditions RI WKH XVXDO HIIHFWLYH SXPSLQJ RI WKH $0 LV ±ƒ& VKRZV that the design of the AE and the functionality of the main units are SUHVHUYHG )RU H[DPSOH )LJ  LV D VHFWLRQHG FHUDPLF GLVFKDUJH FKDQQHO RI D GHYLFH WKDW KDV ZRUNHG PRUH WKDQ  KRXUV $QG

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as can be seen, the integrity of the discharge channel design with electrode assemblies at the ends has been preserved. The results of analysis of long-term tests and operation of pulsed CVLs in continuous and cyclic regimes attest to the high reliability of the designed structures and technology of training of industrial VHDOHGRII VHOIKHDWLQJ $(V RI ERWK WKH .XORQ */  DQG WKH .ULVWDOO */  VHULHV ,W VKRXOG DOVR EH HPSKDVL]HG WKDW DOO PDWHULDOVXVHGLQWKHFRQVWUXFWLRQRIVHDOHG$(&9/H[FHSWIRUKHDW insulators) are widely used in domestic and foreign electrovacuum technology. In all new models of industrial sealed-off AEs on copper vapour of the Kristall series after the completion of the full cycle of training, KLJK DQG SXUH K\GURJHQ JDV ZLWK SDUWLDO SUHVVXUH XS WR ± PP Hg is added to increase and maintain efficiency with prolonged operating time. A powerful series of AE Kristall.7KHILUVWH[SHULPHQWDOVWXGLHV to further increase the radiation power of sealed-off AEs were carried out on a sample whose construction is similar to the industrial AE */& /76L .ULVWDOO  EXW KDV DQ HQODUJHG GLVFKDUJH FKDQQHO OHQJWKE\FPLQWHUHOHFWURGHGLVWDQFHPPVAC FP3). 7KHDYHUDJHUDGLDWLRQSRZHURIWKLVVDPSOHGHVLJQDWHGDV/76L( Kristall, in the case of using an effective thyratron power supply and a plane-spherical resonator with a radius of curvature of the µEOLQG¶ PLUURU RI  P DW D QHRQ SUHVVXUH RI  PP +J DQG WKH N+]35)ZDVDERXW:LQWKHSRZHUDPSOLILHU3$ PRGH : ZKHQ XVLQJ D WZRODPS SRZHU VXSSO\ DQG  N+] 35) LQ WKH 3$ PRGH ±: Among the most promising of the Kristall series of powerful AEs DUHWKHH[SHULPHQWDO$(V.ULVWDOO/7&XDQG³.ULVWDOO/7&X´ 7KH GHVLJQ RI WKH /7&X .ULVWDOO LV FRPSOHWHO\ LGHQWLFDO WR WKH FRQVWUXFWLRQRIWKH.ULVWDOO/7&X>@ZLWKWKHH[FHSWLRQRI WKHGLDPHWHURIWKHGLVFKDUJHFKDQQHOLQWKH$(.ULVWDOO/7&XLW LVPPLHE\PPPRUH7KHH[LWZLQGRZVDUHHQOLJKWHQHGDQG LQFOLQHG WR WKH RSWLFDO D[LV DW DQ DQJOH RI ±ƒ 7KH$( .ULVWDOO /7&X ZDV SURFHVVHG XVLQJ WKH VWDQGDUG WHFKQRORJ\ RI .ULVWDOO devices and filled with neon of high purity with a small addition of K\GURJHQ ± $OO PHDVXUHPHQWV RI LWV RXWSXW SDUDPHWHUV ZHUH carried out in the generator mode using a plane-spherical resonator with a radius of curvature of the ‘blind’ mirror R 3   P 7KH $( ZDVH[FLWHGIURPDSRZHUVRXUFHZLWKDKLJKYROWDJHSXOVHPRGXODWRU EDVHGRQDSRZHUIXOK\GURJHQWK\UDWURQɌ*,ZLWKYROWDJH

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doubling and two optimized links of magnetic compression of pump current pulses (Fig. 3.25). :LWK WZR OLQNV RI PDJQHWLF FRPSUHVVLRQ LQ WKH PRGXODWRU compared to one link, power losses in the thyratron are minimal DQG LWV VHUYLFH OLIH EHFRPHV PRUH WKDQ  K 7KH FDSDFLWDQFH RI the storage capacitor C capGXULQJWKHWHVWLQJYDULHGIURPS)WR S)ZKLFKUHVXOWHGLQDVOLJKWSRZHUFKDQJHIURPWKHUDGLDWLRQ 7KH PD[LPXP YDOXH RI WKH DYHUDJH UDGLDWLRQ SRZHU ZDV REWDLQHG for C cap   S) DQG 35)  N+] :KHQ WKH SUHVVXUH RI WKH EXIIHU JDV RI QHRQ LQ WKH $( .ULVWDOO /7&X YDULHV IURP  WR  PP +J WKH SRZHU RI WKH UDGLDWLRQ

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JUDGXDOO\ GHFUHDVHG E\ DERXW 7KH DPSOLWXGH RI WKH GLVFKDUJH FXUUHQWSXOVHZDVDSSUR[LPDWHO\$ZLWKDGXUDWLRQRIQVDW WKHEDVHDQGDOHDGLQJIURQWRIQV)LJa). The amplitude of WKH YROWDJH SXOVH ZDV a N9 ZLWK D GXUDWLRQ RI  QV RQ WKH EDVH ,Q WKLV PRGH DQ RXWSXW SRZHU RI DERXW  : ZDV DFKLHYHG ZLWK D SRZHU FRQVXPSWLRQ IURP WKH UHFWLILHU RI  N: WKH GLVFKDUJH FKDQQHOWHPSHUDWXUHZDVƒ& ZKLFKFRUUHVSRQGVWRDSUDFWLFDO HIILFLHQF\ RI  7KH XVH RI D WZROLQN PDJQHWLF OLQH IRU WKH compression of current pulses made it possible to reduce both the ORVV LQ WKH WK\UDWURQ RI WKH 7*, 36 PRGXODWRU DQG WR increase the pumping efficiency of the AE. 7KH GHVLJQ RI WKH /7&X .ULVWDOO /7 KDV EHFRPH WKH EDVLV IRU WKH GHYHORSPHQW RI D PRUH SRZHUIXO /7&X .ULVWDOO PRGHO >@ ,WV GLIIHUHQFH IURP WKH EDVLF$( OLHV LQ WKH ORQJHU OHQJWK RI WKH GLVFKDUJH FKDQQHO  PP LQVWHDG RI  PP  DQG PRUH evaporators of copper (seven instead of five). The gas content of the AE was similar to that described above. Measurement of the output characteristics of the AE was also carried out in the mode of the generator, with a radius of curvature of the ‘blind’ mirror of the resonator R 3   P 7R H[FLWH WKH$( DQ 36 ZLWK WKH VDPH high-voltage modulator was used (see Fig. 3.25). The pulses of the YROWDJH DQG FXUUHQW RI WKH /7&X .ULVWDOO )LJ  b) had the VDPHGXUDWLRQDVWKHSXOVHVRIWKH/7&X.ULVWDOOEXWZHUHVOLJKWO\ ODUJHU LQ DPSOLWXGH 7KH PD[LPXP RXWSXW SRZHU RI WKH /7&X .ULVWDOO UHDFKHG  : DW  N+] 7KH GXUDWLRQ RI WKH JHQHUDWLRQ SXOVHDORQJWKHEDVHZDV±QVDWDQHRQSUHVVXUHRIPP+J 7KHUDGLDWLRQSRZHURQWKH\HOORZDQGJUHHQOLQHVLVDERXWDQG  RI WKH WRWDO SRZHU UHVSHFWLYHO\ $W WKH VDPH WLPH WKH SRZHU FRQVXPHGIURPWKHUHFWLILHUZDVN:ZLWKORVVHVLQWKHWK\UDWURQ a N: ORVVHV ZHUH PHDVXUHG E\ WKH FDORULPHWULF PHWKRG  DQG SUDFWLFDO HIILFLHQF\ UHVSHFWLYHO\  The achieved values of the average radiation power in a pulsed &9/ZLWKH[SHULPHQWDO$(V.ULVWDOO/7&XDQG/7&X.ULVWDOO ±  DQG  : ± ZHUH REWDLQHG LQ WKH PRGH RI WKH JHQHUDWRU LH with an optical resonator. However, from a practical point of view, it is more preferable to use these long Kristall AEs in high-power ODVHUV\VWHPVRQFRSSHUYDSRXU&9/6 RIWKH02±3$W\SHDVD3$ ZKHQWKHRXWSXWSRZHULQFUHDVHVE\PRUHWKDQVHH7DEOH  7KHUHIRUHLWFDQEHDUJXHGWKDW$(.ULVWDOO/7&XDQG.ULVWDOO/7 &XZKHQXVHGDVDPSOLILHUVZLOOJLYHDQLQFUHDVHLQWKHUDGLDWLRQ SRZHU WR  DQG  : UHVSHFWLYHO\ 7KHVH YDOXHV FRUUHVSRQG WR

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AE C cap a

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AE C cap L sh

b

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AE C cap

C cap

C sc

c 7*,

C cap

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C cap L sh

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7*, Fig. 3.27.%DVLFHOHFWULFDOVFKHPHVIRUWKHH[HFXWLRQRIKLJKYROWDJHSXOVHPRGXODWRU of the power source of the CVL: a and b are direct circuits with thyratron and lamp switches; c and d±VFKHPHVRIWUDQVIRUPHUDQGFDSDFLWLYHYROWDJHGRXEOLQJZLWKD link of magnetic compression of current pulses; e ± VFKHPH RI FDSDFLWLYH YROWDJH doubling with two links of magnetic compression and anode reactor.

D VSHFLILF SRZHU WDNHRII RI DERXW  :FP 3, which is 1.5 times OHVV WKDQ WKDW RI WKH DQDORJXH ± /7&X .ULVWDOO */&  7KH decrease in the power take-off is due, first of all, to the increase in

New Generation of Efficient Sealed-off Active Elements

115

the diameter of the discharge channel, since it leads to a decrease in the degree of restoration of the AM in the interpulse period. As it was mentioned above, the important parameters for the highSRZHU$( .ULVWDOO FODVV DUH WKRVH ZKHQ RSHUDWLQJ LQ WKH 3$ PRGH which include the radiation power, specific power take-off, practical HIILFLHQF\ DQG $( HIILFLHQF\ +LJK YDOXHV RI UDGLDWLRQ SRZHU   :  SUDFWLFDO HIILFLHQF\ RI &9/ ±  DQG$( HIILFLHQF\ ±  WHVWLI\ WR WKHLU HIIHFWLYH XVH LQ KLJKSRZHU ODVHU V\VWHPV RQFRSSHUYDSRXU&9/6 RIWKHW\SH02±3$XVHGLQWHFKQRORJLFDO equipment for the selective separation of isotopes. 8QIRUWXQDWHO\LQ5XVVLDIRUH[DPSOHLQWKHKurchatov Institute, in recent years, the development of a progressive technology for the laser separation of isotopes and the production of highly pure substances has been suspended for ‘incomprehensible’ reasons, which in turn inhibits the implementation of new developments to create a powerful class of industrial sealed-off AE of the pulsed CVL. Studies of the efficiency of pumping CVL with different execution of the electrical circuit of the high-voltage pulse modulator of the power source. In addition to design and WHFKQRORJLFDO VROXWLRQV WKH FRQGLWLRQV IRU SXPSLQJ H[FLWDWLRQ  RI the active medium of the AE provided by high-voltage power sources of nanosecond pulses have a significant effect on the power and HIILFLHQF\ RI WKH &9/ 2XU H[SHULPHQWDO VWXGLHV DQG LQYHVWLJDWLRQV E\ PDQ\ DXWKRUV VKRZ WKDW HIIHFWLYH H[FLWDWLRQ FRQGLWLRQV DUH achieved primarily by reducing the duration of the leading edge of discharge current pulses, i.e., increasing the rate of its increase VWHHSQHVV  DQG WRWDO GXUDWLRQ %XW WKH PD[LPXP UDGLDWLRQ SRZHU and efficiency are reached at current durations close to the time of H[LVWHQFHRIWKHSRSXODWLRQLQYHUVLRQLHSUDFWLFDOO\WKHGXUDWLRQRI WKH UDGLDWLRQ SXOVHV >±@7KHVH FKDUDFWHULVWLFV RI WKH H[FLWDWLRQ SXOVHVHVVHQWLDOO\GHSHQGRQWKHH[HFXWLRQRIWKHHOHFWULFDOFLUFXLWRI the high-voltage modulator of the power source and the inductance of the discharge circuit. Figure 3.27 shows schematic circuit diagrams of high-voltage research with industrial sealed-off AEs of the Kulon and Kristall VHULHV >    ± ± ± ±@ In the schemes a, c, d and e, water-cooled hydrogen thyratrons RI WKH W\SH 7*,± 7*, DQG 7*, >@ were used as a high-voltage pulse commutator. The durability of thyratrons with circuit a  LV XVXDOO\ ± K DQG DW D 35) DERYH ±N+]WKH\RSHUDWHXQVWDEO\ZKLFKLVPDQLIHVWHGLQWUDQVLWLRQV

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from the pulsed regime to the regime of continuous arc discharge. To HQVXUHRSHUDWLRQDWKLJK35)XSWRN+] ZDWHUFRROHGK\GURJHQ WDFLWURQV RI WKH W\SH 7*8 ZHUH XVHG ,Q WKH HOHFWULFDO circuit b DZDWHUFRROHGYDFXXPODPS*0,$LVXVHGDVDSXOVH switch, which makes it possible to generate short pump pulses with D ± 2 N+] 35) >@ 7KH H[FLWLQJ FXUUHQW SXOVHV LQ VHOIKHDWLQJ $(V DOVR SURYLGH heating of the discharge tube with an active substance (copper) XS WR ±ƒ& WKHUHIRUH LW LV QHFHVVDU\ WR REVHUYH FHUWDLQ relationships between the duration of the current pulses, their DPSOLWXGH DQG 35) 7KH HOHFWULFDO FLUFXLW RI WKH QDQRVHFRQG SXOVH modulator, shown in Fig. 3.27 aLVWKHVLPSOHVWVFKHPHIRUH[FLWDWLRQ of the active medium of the CVL. This scheme is called direct, in VRPH ZRUNV ± FODVVLFDO RU WUDGLWLRQDO 7KH QDPH µGLUHFW VFKHPH¶ largely reflects its physical essence. The operation of the direct VFKHPH ZDV FRQVLGHUHG LQ PDQ\ ZRUNV EXW LQ PRUH GHWDLO LQ >@ The circuit operates in the full discharge mode of the storage capacitor through a thyratron. In this scheme, resonance charging of a storage capacitor with a capacitance Cn via a nonlinear charge choke with an inductance of L ch§+RFFXUVDQGDVKXQWLQGXFWRU with an inductance of L sh  §  ȝ+ IURP D KLJKYROWDJH UHFWLILHU (HR). Using the choke L ch as a charging line allows increasing the voltage on the capacitor C cap to values that are twice the voltage of WKHH[SORVLYH,QUHDOZRUNLQJFRQGLWLRQVWKHYROWDJHRQWKHC cap as DUHVXOWRIUHFKDUJLQJLQFUHDVHVE\DQRWKHURUPRUH7KHJUHDWHU the mismatch between the modulator and the AE, the greater the voltage will be on the Ccap)RUH[DPSOHDVWKHSUHVVXUHRIWKHEXIIHU gas increases, the resistance of the AE increases and the degree of FKDUJH H[FKDQJH RI WKH VWRUDJH FDSDFLWRU GHFUHDVHV ZKLFK FDXVHV D decrease in the power consumed from the rectifier. The inductance of the choke LshLVXVXDOO\±ȝ+±WKLVYDOXHLVVXIILFLHQWWRQRW shunt the AE discharge during commutation. In addition, the inductor with inductance Lsh short-circuits the discharge gap of the AE during the interpulse period. A sharpening capacitor with a capacitance C sc , connected in parallel with the AE, performs the function of H[DFHUEDWLQJ WKH IURQW RI WKH FXUUHQW SXOVHV LH DQ LQFUHDVH LQ WKH UDWH RI FXUUHQW ULVH 2QH WHUPLQDO RI WKH VKDUSHQLQJ FDSDFLWRU LV connected directly to the cathode (high-voltage electrode) of the AE, DQGWKHRWKHUWKURXJKDFRD[LDOPHWDOOLFFRSSHURUDOXPLQXP FXUUHQW lead to its anode. The inductance of such a circuit is insignificant DQGDPRXQWVWR±ȝ+8VXDOO\WKHRSWLPXPFDSDFLWDQFHRICsc is

New Generation of Efficient Sealed-off Active Elements

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±WLPHVOHVVWKDQWKHFDSDFLWDQFHC cap. The sharpening capacitance in combination with the return current leads to an increase in the UDGLDWLRQ SRZHU E\ ± 'HVSLWH WKH VLPSOLFLW\ D GLUHFW FLUFXLW can not always be used, since the pumping of the AE is ineffective in its application. This is due to the fact that during the discharge of the current, the thyratron, the storage capacitor, and the AE are turned on in series, that is, they form a single discharge circuit, and the parameters of the pulses directly depend on the rate of discharge GHYHORSPHQW LQ WKH WK\UDWURQ >@ In the first industrial CVL Kriostat, the modulator of the power VXSSO\,3ZDVPDGHLQDGLUHFWVFKHPH:LWKDVWRUDJHFDSDFLWDQFH Ccap S)DQGDN+]35)WKHDYHUDJHUDGLDWLRQSRZHULV± :DQGWKHSUDFWLFDOHIILFLHQF\LV±2QHRIWKHPDLQUHDVRQV for the low efficiency is the long duration of the discharge current SXOVHV a QV  $ ODUJH YROXPH RI H[SHULPHQWDO VWXGLHV XVLQJ D GLUHFWPRGXODWRUH[HFXWLRQVFKHPHLVJLYHQLQ5HIV>@IRUWKH VHDOHGRII$(*/,QWKHUDQJHRI±N+]35)FDSDFLWDQFHV Ccap ±S)DQGEXIIHUJDVSUHVVXUHVRI±PP+JWKH duration of the front and the total duration of the current pulses were ± DQG ± QV UHVSHFWLYHO\ DW DPSOLWXGHV RI ±$ The current pulses through the AE were detected by a Rogowski coil operating in the current transformer (CT) mode, the voltage pulses by the compensated voltage divider (VD) and the oscilloscope C175 (see Fig. 3.27 a). Since the duration of the current pulses for a GLUHFW SXPSLQJ VFKHPH LV ± WLPHV DQG LQ VRPH FDVHV DQG E\ DQ order of magnitude greater than the duration of the radiation pulses, LW ZDV LPSRVVLEOH WR H[SHFW KLJK YDOXHV RI WKH UDGLDWLRQ SRZHU DQG HIILFLHQF\7KHHIILFLHQF\ZDVDERXWDWUDGLDWLRQSRZHUVRI± :,QWKLVVFKHPHWKHVHUYLFHOLIHRIWK\UDWURQVLVWRRVKRUWGXH WR ODUJH LQLWLDO ORVVHV  ± ± KRXUV 7R HQVXUH VWDEOH RSHUDWLRQ of the thyratron it is necessary to stabilize the heating voltage of its hydrogen generator and cathode. Nevertheless, this scheme was used LQ &9/V IRU DERXW  \HDUV XQWLO WKH HDUO\ V To obtain the same high radiation power and efficiency, it is QHFHVVDU\WRUHGXFHWKHWRWDOGXUDWLRQRIWKHFXUUHQWSXOVHVWR± QVZLWKWKHIURQWGXUDWLRQXSWR±QVLHWRDYDOXHFORVHWRWKH WLPHRIH[LVWHQFHRIWKHSRSXODWLRQLQYHUVLRQ6XFKFKDUDFWHULVWLFVDUH almost impossible to obtain in the direct modulator design described above, since the thyratron can not commute large average powers when operating with short current pulses following with a high frequency.

118

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The first work in Russia (USSR), in which the conditions of H[FLWDWLRQ RI &9/ ZHUH VLJQLILFDQWO\ LPSURYHG ZDV SXEOLVKHG LQ  >@ 7KH SULQFLSDO HOHFWULFDO FLUFXLW RI D SXOVHG SXPS PRGXODWRU DSSOLHG LQ >@ LV VKRZQ LQ )LJ  c. This circuit allows one to double the amplitude of the voltage and reduce the duration of the current pulses by half. The scheme uses a pulsed autotransformer and a link of magnetic compression on ferrites (non-linear saturable choke). The pulsed autotransformer with the  WUDQVIRUPDWLRQ UDWLR LV PDGH RQ WKH EDVLV RI VL[ 11 IHUULWH ULQJVZLWKGLPHQVLRQV.îîPPDQGJDSVEHWZHHQWKHP (1 mm) to improve cooling. The winding is made with a cable with IOXRURSODVWLFLQVXODWLRQ397)(WKHQXPEHURIWXUQVLV7KHEUDLG and the central core are connected in series. The turns are isolated from each other and from the ferrite core by means of fluoroplastic rings with grooves. The transformer operated with forced air cooling. The non-linear choke with inductance L2FRQVLVWHGRIIHUULWHULQJV 10$ ZLWK GLPHQVLRQV .  î  î  PP ZLWK FRSSHU ZLUH SDVVHG WKURXJK WKHP7KH FKRNH ZDV SODFHG LQ D JODVV WXEH  PP in diameter and cooled by running water. The capacitance of the storage capacitor C cap ZDV  S) WKH ZRUNLQJ FDSDFLWRU C cap §  S) WKH VKDUSHQLQJ FDSDFLWRU C sc §  S) ,Q > ± @ WKH FLUFXLW ZLWK WUDQVIRUPHU YROWDJH doubling and the link of magnetic compression was used to increase WKHH[FLWDWLRQHIILFLHQF\RIWKH.ULVWDOOW\SH$(VRIWKH*/DQG */'W\SH,Q>@WKHSXOVHGDXWRWUDQVIRUPHULVPDGHRQWKUHH IHUULWH ULQJV RI WKH 11 EUDQG ZLWK WKH GLPHQVLRQV .  î  î  PP %HWZHHQ WKH ULQJV DQ DLU JDS ± PP  LV IRUPHG ZLWK the help of cardboard pads. The winding is made with a wire with a copper conductor cross-section of 1.5 mm 2, the number of turns is 16. To isolate the wire from the core and the turns, discs from sheet SOH[LJODVVZLWKKROHVIRUVWUHWFKLQJWKHZLQGLQJZLUHZHUHXVHGIURP each other. This transformer is more reliable in electric strength than WKHRQHXVHGLQ>@7KHGHVLJQRIWKHQRQOLQHDUFKRNHL 1) given LQ >@ LV VLPSOHU D ZDWHUFRROHG FRSSHU WXEH ZLWK 010 IHUULWH ULQJV VWUXQJ RQ LW ZLWK VL]HV .  î  î  PP WKH QXPEHU RI ZKLFK UHDFKHV  The circuit in Fig. 3.27 works as follows. Resonant charging of the capacitor C cap is realized from the high-voltage rectifier through the throttle L ch and the input winding of the autotransformer T p . After opening the thyratron, the capacitor C cap is recharged through the input winding of the autotransformer T p to the capacitor

New Generation of Efficient Sealed-off Active Elements

119

C cap /4. The parameters of the choke L 1 were selected so that it would become saturated only after the capacitor C cap/4 was fully charged. After saturation of the throttle L 1, the capacitor C cap/4 is rapidly discharged to C sc and through the AE. Due to the fact that the working capacitance for AE is the capacitance C cap/4, the total duration of the current pulse through the AE is half as much as in the direct circuit, where the working capacitor C cap discharges directly to the AE through the thyratron. The thyratron thus works in the facilitated mode on the speed of increase of a current as the load is not AE, and an input winding of the transformer Ɍ ɪ. The service life RIWK\UDWURQVLQFUHDVHVWRKRXUVRUPRUH7KLVFLUFXLWc) worked VWHDGLO\ RQ WKH 35) IURP  WR  N+] ZLWK DQ DYHUDJH VZLWFKLQJ SRZHU RI XS WR  N:7KH GXUDWLRQ RI WKH IURQW RI WKH SXOVHV RI WKH H[FLWLQJ FXUUHQW GHSHQGLQJ RQ WKH SDUDPHWHUV RI WKH FLUFXLW FRXOG YDU\ IURP  WR  QV WKH DPSOLWXGH IURP  WR  N$ ZLWK D FKDQJH LQ WKH YROWDJH DFURVV WKH$( IURP  WR  N9 )RU WKH ILUVW WLPH LQ >@ WKH UDGLDWLRQ SRZHU RI WKH$(7/* .ULRVWDW  ZLWK FLUFXLW E DW WKH  N+] )3, ZDV LQFUHDVHG IURP  WR  : WZLFH  */ IURP  WR : The circuit d LQ )LJ  >@ E\ WKH SULQFLSOH RI RSHUDWLRQ DQGHIILFLHQF\RIH[FLWDWLRQSUDFWLFDOO\GRHVQRWGLIIHUIURPVFKHPH c. But from the point of view of design it is simpler and leads to less power losses. This is due to the fact that the doubling of the voltage in the case of using the scheme d (according to the Blomlein VFKHPH >@  LV FDUULHG RXW RQ KLJKIUHTXHQF\ FDSDFLWRUV ZLWKORZ losses. In scheme b DERXW  RI WKH WK\UDWURQVZLWFKHG SRZHU is dissipated in a ferrite transformer T p, which requires additional (forced) air cooling. In the circuit, resonant charging of the working capacitors with a capacitance C cap/2 from the high-voltage rectifier HR is carried out through a charge choke (L ch), a non-linear choke (L) and an air reactor (L   2QH RI WKH ZRUNLQJ FDSDFLWRUV ZLWK D capacitance of C cap/2 (the upper one in the diagram) is connected to the ‘ground’ through the chokes L 1 and L sh, and the other (bottom) ± GLUHFWO\$IWHU RSHQLQJ WKH WK\UDWURQ WKH ERWWRP FDSDFLWRU C cap/2 is recharged (inverted) and, as a result, the voltage doubles on the capacitors connected in series. After saturation of the reactor L 1 (as well as in circuit c), there is a rapid discharge of working capacitors Ccap/4 to Csc and via AE. The non-linear choke L (thyractor), designed WRUHGXFHWKHVWDUWLQJORVVHVLQWKHWK\UDWURQ>@LVDZDWHUFRROHG FRSSHUWXEHZLWKIHUULWHULQJVWKUHDGHGRQLWIRUH[DPSOH010 ZLWK GLPHQVLRQV .  î  î  PP WKH QXPEHU RI ZKLFK UHDFKHV

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±6XFKDWK\UDFWRUUHWDUGVWKHGHYHORSPHQWRIWKHDQRGHFXUUHQW RI WKH WK\UDWURQ ZLWK UHVSHFW WR WKH YROWDJH E\ ± QV :LWK a longer delay, with one compression link, the characteristics of the pump pulses of the AE deteriorate. The L  choke is necessary to match the recharge time of the lower capacitor C cap/2 with the delay in the development of the discharge in the AE and is units of microhenry. The circuit d with capacitive voltage doubling has practically no fundamental limitations on switched power, which is important for pumping AE with a large power consumption. To do this, firstly, to increase the duration of the pulses of the anodic current of the WK\UDWURQ E\ WZR WLPHV RU PRUH XS WR ± QV  DQG LQ WKH same way to its amplitude, which leads to a decrease in the initial losses to a minimum (due to an increase in inductance L) and, secondly, to increase the number of magnetic compression links for the subsequent reduction of the duration of the current pulses to the PLQLPXP YDOXH >±@ Figure 3.27 e shows a circuit with a capacitive voltage doubling with two links of magnetic compression and an anode reactor. The PRVW SRZHUIXO GRPHVWLF WK\UDWURQ Ɍ*, LQ WKLV VFKHPH DOORZV VZLWFKLQJ PHGLXP SRZHU WR ± N: ,Q WKLV VFKHPH thyratrons operate in a lightweight mode (in the minimum loss mode) DQG WKHLU VHUYLFH OLIH LV ± K The indisputable advantages of vacuum lamps as controllable devices are the possibility of forming the fronts of current pulses ZLWK D GXUDWLRQ RI ± QV ZLWK D WRWDO GXUDWLRQ RI ± QV DQG RSHUDWLRQDWD35)RI±2 kHz. The main disadvantage of vacuum lamps is the relatively small values of the peak amplitude of the anode current pulses due to the saturation current limitation. In the FDVH RI XVLQJ WKH *0, $ ODPS WKH DPSOLWXGH RI WKH FXUUHQW SXOVHV GRHV QRW H[FHHG ±$ DQG WKH YDOXHV RI WKH VZLWFKHG DYHUDJH SRZHU DUH ± N: ,Q FLUFXLW b WKH *0, $ ODPS operates in the partial discharge mode of the storage capacitance Ccap. At present, work is underway to replace water-cooled hydrogen thyratrons and vacuum lamps with more compact solid-state switches. >@ FRQVLGHUHG D SRZHU VRXUFH XVLQJ WK\ULVWRU VZLWFKHV ZLWK D SRZHUFRQVXPSWLRQRIN:SURYLGLQJDSDVVSRUWPRGHRIRSHUDWLRQ IRUWKH$(.XORQ/7&X>@7KHDXWKRUVRI>@VXJJHVW the development of such a power source for the Kulon LT-5Cu AE >    @$SRZHUVRXUFHZLWKDWUDQVLVWRUZUHQFKIRU

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pumping a &X%UODVHUZDVFUHDWHG>@7KHVZLWFKHGFDSDFLW\ZDV  N: WKH UDGLDWLRQ SRZHU ZDV : To g e t h e r w i t h a g r o u p o f s p e c i a l i s t s o f t h e M a t e r i a l y mikroelektroniki, a two-channel transistor power supply for the &9/6.XORQDQG.XORQZLWKFRPPHUFLDOVHDOHGRII$(.XORQ /7&X*/' DQG.XORQ/7&XȽɅ, >@ZRUNLQJ DFFRUGLQJ WR WKH VFKHPH 02±3$ ZDV FRQVWUXFWHG ,Q HDFK FKDQQHO with two pulse transformers and three magnetic compression links, voltage pulses with an amplitude of ~17 kV and current pulses with DQDPSOLWXGHRIa$DQGDGXUDWLRQRIDERXWQVDUHJHQHUDWHG DWD35)RI±N+]7KHSRZHURIHDFKFKDQQHOLVN:6WXG\ >@UHSRUWHGRQWKHFUHDWLRQRIDSXOVHGSRZHUVXSSO\RQWUDQVLVWRU VZLWFKHVZLWKDVZLWFKHGSRZHURIXSWRN:IRUSXPSLQJD ZDWW K\EULG FRSSHU YDSRXU ODVHU &X±1H±+%U  In addition, together with the VELIT company the work on the FUHDWLRQ RI PRGHUQ LQGXVWULDO &9/ .XORQ ZLWK WKH $( PRGHO */'DQG.XORQZLWKWKH$(PRGHO*/,ZLWKWKHXVHRI transistor switches is being completed with the high reliability and efficiency. These commercial lasers have no domestic and foreign analogs. At present, the Kulon and Kristall CVLs are mainly pumped with power sources with capacitive voltage doubling, magnetic compression links and anode reactor (circuit e), which, due to a IROGGHFUHDVHLQWKHGXUDWLRQRIWKHFXUUHQWSXOVHVXSWR± ns), in comparison with the classical version of the power source, HQDEOH GRXEOLQJ WKH UDGLDWLRQ SRZHU )LJ   >   @ However, the working temperature of the discharge channel of WKH$( LQFUHDVHV E\ DERXW ƒ& IURP ƒ& WR ƒ& :LWK D ODPSSRZHUVRXUFHWKHWHPSHUDWXUHULVHVHYHQPRUH±XSWRƒ& Therefore, the temperature of the discharge channel of the AE CVL GXULQJ WKH WUDLQLQJ RQ GHJDVVLQJ LV DGMXVWHG WR ƒ& Basic parameters and characteristics of industrial sealed-off AE of the Kulon series. The main parameters of industrial sealed-off VHOIKHDWLQJ$(VRIWKH.XORQVHULHV*/DFFRUGLQJWR78 SXOVHG &9/DQG*9/DUHSUHVHQWHGLQ7DEOH7KH$(RIWKH.XORQVHULHV KDYH UHODWLYHO\ VPDOO GLPHQVLRQV ± OHQJWK ± P VHH 7DEOH   SRZHU FRQVXPSWLRQ LQ WKH UDQJH RI ± N: VHH 7DEOH  DPHWDO±JODVVYHUVLRQRIDYDFXXPWLJKWVKHOODQGDUHRSHUDWHG mainly in the air cooling mode. The most powerful of this series of $( */' DQG */, DUH XVHG LQ WHFKQRORJLFDO LQVWDOODWLRQV such as Karavella, intended for microprocessing of electronic

± ± ± 3:2 ± 6

3XOVHUHSHWLWLRQIUHTXHQF\35)  optimum operating range, kHz

Average radiation power in the generator mode IRUWKHRSWLPXP35) :

Radiation power ratio **

The duration of the radiation pulses (at halfheight), ns

Divergence of radiation with a plane resonator, mrad

Divergence of radiation with a telescopic unstable resonator, mrad

 4.2

Length of the discharge channel, mm

7

Active medium volume, cm3



Diameter of the discharge channel, mm

*/ $

The pressure of the buffer gas Ne, mm Hg

Radiation wavelength, nm

Laser environment

3DUDPHWHU

± ±

28



12



5.5

±

3:2

6

±

3.5 : 2

*/ ' 8/

Model

6.5

±

3.5 : 2

±

± ±

38



14



*/ (

4.5

±

3:2

15

± ±

65



14



±PUDG

7

±

5:3

±

± ±

116









Copper vapours

*/ &

± ±

± ±

5.7

175

7

*/ %

4.3

±

3:2



± ±

85

625

14



*/ ,

*/ *



6

±

±

±

± ±

38



14

4

±

±

±

± ±

65



14



627.8

*ROGYDSRXUV

*/ )

Table 3.3 The main parameters of a new generation of industrial sealed self-heating AE of the Kulon series

122

Laser Precision Microprocessing of Materials

  Service life not less than, h

 +LJKYROWDJH SXOVH PRGXODWRU SRZHU VRXUFH LV H[HFXWHG XQGHU WKH VFKHPH RI FDSDFLWLYH YROWDJH GRXEOLQJ ZLWK WZR OLQNV RI PDJQHWLF compression of nanosecond current pulses. The capacity of the storage capacitor is 2C S)WKHVKDUSHQLQJFDSDFLWRULVC ob  pF. ** P isla Ȝ   QP P is Ȝ   QP 



> > > > > > > > > Minimum operating time, h

      45 25 Readiness time (at optimum power consumption), min

25

1.15   3RZHUFRQVXPHGIURPWKHUHFWL¿HURIWKHSRZHU VRXUFHN:

Table 3.3

±

±

±

2.1

1.4



New Generation of Efficient Sealed-off Active Elements

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materials. Therefore, to ensure the stability of the position of WKH EHDP D[LV WKH KHDWORDGHG AE is installed inside the watercooled cylindrical metal heat sink, which simultaneously performs the function of the reverse current conductor. As can be seen from Table 3.3 the working pressure of neon EXIIHU JDV LQ WKH $( RI */ $ ZLWK D UDGLDWLRQ SRZHU RI :DQG*/%ZLWKDSRZHU RI  : LV  PP +J */ & SRZHU RI  : ±  PP +J */' ZLWK D SRZHU RI :±PP+JVWDQG*/ , SRZHU RI  : ±  PP Hg. Art. The buffer gas pressure in sealed AEs is selected by a compromise solution between the longevity and the radiation power. The durability of the sealed AE is higher, the more the mass of copper in the copper vapour generators, the distance from the generators to the copper vapour condensers, and the neon pressure. The high pressure of neon in malaborite AE is the main and necessary condition for ensuring their high longevity, since large amounts of active substance can not be constructively made in short discharge channels, and the length of the path for diffusion RI FRSSHU YDSRXU IURP H[WUHPH generators to condensers is always limited. In the AE model * /     $ R Q O \  W Z R  F R S S H U

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21 kV

12 kV 0.28 kA

0.38 kA

50 ns

tp = 100 ns tp = 50 ns

tb = 250 ns

a

b

tb = 130 ns

320 A

21 kV

20 ns

c Fig. 3.28. 2VFLOORJUDPV RI YROWDJH SXOVHV 1), current (2) and radiation (3) of WKH &9/ ZLWK WKH .ULVWDOO */$ $( ZLWK GLIIHUHQW H[HFXWLRQ RI KLJKYROWDJH modulator of the power source.

YDSRXU JHQHUDWRUV DUH SODFHG  J HDFK */% ± WKUHH DQG DOVR  JUDPV LQ */% ± WKUHH  J HDFK */' WKUHH */ , ± IRXU IRU  J ,Q SUDFWLFDOO\ DOO NQRZQ ZRUNV RQ SXOVHG CVLs both in the sealed-off mode and in the pump gas pumping UHJLPH WKH PD[LPXP UDGLDWLRQ SRZHUV DUH DWWDLQHG DW UHODWLYHO\ ORZ QHRQ SUHVVXUHV ± PP +J 7RJHWKHU ZLWK WKH HPSOR\HHV of VELIT Co, a high-voltage pulse thyratron power source was developed and optimized, the modulator of which was designed in accordance with the capacitive voltage doubling scheme with two links of magnetic compression of nanosecond current pulses and an anode reactor (Fig. 3.27 d >@ZKLFKPDNHVLWSRVVLEOH to produce highly effective pumping of the AE of the Kulon series even at neon pressures close to atmospheric. The power source was FRROHG ZLWK IRUFHG DLU :LWK WKLV FLUFXLW ZLWK DPSOLWXGH YROWDJHV RI ± N9 FXUUHQW SXOVHV ZLWK D WRWDO GXUDWLRQ RI ± QV DQG DQ DPSOLWXGH RI ±$ DUH JHQHUDWHG ZLWK D IURQW GXUDWLRQ RI QR PRUH WKDQ  QV ZKLFK FRUUHVSRQGV WR WKH WLPH RI H[LVWHQFH of population inversion in the active medium, i.e., practically the duration of radiation pulses. The the average radiation power levels

New Generation of Efficient Sealed-off Active Elements

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P , W p"" rad' BT

TT. , ,°C chan 1600

P rad

1500 1400

TT.chan

18 16 14 12 10

1300

8 6 4 2

1200 14

15

16

17

18

kW 19 P P rect sbl np, , K8T

Fig. 3.29. Dependence of the average radiation power (P rad) and temperature of the discharge channel (T chan RIWKH$(.XORQPRGHO*/'RQWKHSRZHUFRQVXPHG from the rectifier powder source.

P, mmHg P , MM. pT. CT .

cm –3

10

10

5

5

1400

1600

1800 T, °C

Fig. 3.30. The dependence of concentration (1) and pressure (2) of copper vapour on temperature.

SUHVHQWHG LQ 7DEOH  FRUUHVSRQG WR WKH PD[LPXP YDOXHV REWDLQHG when optimizing the CVL for the power consumption in the range RIWKHRSHUDWLQJ35)DQGLQWKHVWHDG\VWDWLRQDU\ WKHUPDOUHJLPHV )RU H[DPSOH IRU WKH$( */' DW  N+] WKH PD[LPXP SRZHU (P rad   :  ZKLFK LV DOVR WKH ZRUNLQJ RQH LV VHW DW WKH SRZHU consumption of the power source rectifier P rect  ± N: DQG the temperature of the discharge channel T chan  o&)LJ  *HQHUDWLRQ LQ WKH $( EHJLQV DW P rect    N: ZKHQ T chan   ƒ&$WDWHPSHUDWXUHTchan ƒ&WKHFRQFHQWUDWLRQRIFRSSHU vapour is n   14 cm í, at T chan  ƒ& ± n   ā  15cm í (see )LJ  

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1,4

1,5

1,6

1,7

1,8

1,9 PPabmp ,, KBT kW rect

Fig. 3.31.'HSHQGHQFHRIWKHHIILFLHQF\RIWKHODVHU$(.XORQPRGHO*/(RQ the power consumed from the rectifier of the power source.

I, A

U,KB U, kV

15

300

10

200

5

100 0

0

40

80

120

160

200

240

280

t, ns

Fig. 3.32. 2VFLOORJUDPVRIYROWDJHSXOVHVU) and current (I) of the laser AE Kulon, PRGHO */(

U, U, kV KB 20

15 10 5 0

50

t, ns

Fig. 3.33. 2VFLOORJUDP RI YROWDJH SXOVHV RI WKH ODVHU$( .XORQ PRGHO */,

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127

P rad/V AM BT W/cm3

20

P H3R

3 - ,-

VAc

CM

0,35

15 0,3 10

2

0,25 0,2

5

0

20

40

60

0 3 3 , cm 80 V VAc, AM cM

Fig. 3.34. Dependence of the average power (P rad) (1) and specific (P rad/V AC) (2) radiation power of the industrial sealed-off laser AE of the Kulon series on the volume of the active medium (AM).

At a power consumption P rect !  N: ZKHQ WKH WHPSHUDWXUH Tchan !ƒ&WKHUHLVDVKDUSGHFUHDVHLQWKHUDGLDWLRQSRZHUZKLFK is due to the thermal population of metastable levels of copper atoms. 7KHPD[LPXPUDGLDWLRQSRZHUFRUUHVSRQGVWRDPD[LPXPHIILFLHQF\ equal to Ș   )LJ   The pulses of the voltage and discharge current of the AE Kulon RI WKH */( PRGHO DUH VKRZQ LQ )LJ  :LWK WKH RSWLPXP power consumption (P rect    N9  DQG WKH ZRUNLQJ 35) RI  kHz the amplitude of the voltage pulses (U) is 16 kV for a base GXUDWLRQ RI a QV FXUUHQW J  LV $ IRU D GXUDWLRQ RI a QV The duration of the steep portion of the front of the current pulses LVaQVDQGFRUUHVSRQGVWRWKHPHDVXUHGYDOXHVRIWKHGXUDWLRQRI the radiation pulses. :LWK DQLQFUHDVHLQ WKHOHQJWKRIWKHGLVFKDUJH FKDQQHOLQRUGHU to increase the efficiency of the AE, it is also necessary to increase WKHDPSOLWXGHRIWKHYROWDJHSXOVHV,QWKHORQJHVW$(*/,ZLWK DSRZHUXSWR:WKHYROWDJHDPSOLWXGHLQWKHRSWLPDORSHUDWLQJ mode is 21 kV (Fig. 3.33). An important physical indicator of the efficiency of AE operation is the removal of power from a unit volume of the active medium. Figure 3.34 shows the dependences of the mean (Prad) (1) and specific (P rad/V AM) (2) radiation power for industrial sealed-off AE of the

128

Laser Precision Microprocessing of Materials

.XORQVHULHV*/DFFRUGLQJWR78 RQWKHYROXPHRIWKHDFWLYH medium are presented. The radiation power increases with an increase in the volume of the active medium (curve 1), and the specific power density falls FXUYH WKDWLVLWGRHVQRWUHPDLQDFRQVWDQWYDOXH,IWKH$(*/ $ ZLWK WKH YROXPH RI$0 RI  FP 3 the specific power (power UHPRYDO SHU XQLW YROXPH  LV  :FP 3 WKHQ LQ */, ZLWK DQ AM volume of 85 cm 3 LV  :FP 3 (1.5 times less). The latter, first of all, is associated with a decrease in the optimum operating temperature of the discharge channel and, correspondingly, the FRQFHQWUDWLRQRIFRSSHUYDSRXULQWKH$0,QWKH$(*/$DQG */%WKHZRUNLQJWHPSHUDWXUHRIWKHGLVFKDUJHFKDQQHOZLWKDQ LQWHUQDO GLDPHWHU RI  PP UHDFKHV ƒ& n   16 cm í  LQ */ ,DQG*/,ZLWKDFKDQQHOGLDPHWHURIPPWKHWHPSHUDWXUH LV DERXW ƒ& n   ā  15 cm í). The smaller the diameter of the discharge channel, the higher the rate of settling (decay) of the metastable levels of copper atoms in the interpulse period (due to the relative increase in the number of collisions of atoms with the channel wall), the higher the permissible operating temperature and the specific radiation power. Conversely, the larger the volume of speakers due to the increase in the diameter of the channel, the lower the rate of decomposition of metastable levels and, correspondingly, the operating temperature of the channel and the specific power. The minimum (guaranteed) operating time of industrial sealedRII $(V RI WKH */$ DQG */% PRGHOV RI WKH SXOVHG &9/ LV DW OHDVW  K T chan  ƒ&  RI WKH$( */& */' */( DQG */, ±  K T chan  ƒ&  ZKLFK LV D TXLWH acceptable level for this class of lasers and their wide application in modern technological and medical equipment. Limitation of the RSHUDWLQJ WLPH RI $(V RQ JROG YDSRXU */) DQG */* WR KLVGXHWRWKHLQFUHDVHGRSWLPXPRSHUDWLQJWHPSHUDWXUHRIWKH GLVFKDUJHFKDQQHO,WLVKLJKHUE\±ƒ&WKDQWKH$(RQFRSSHU vapour.) During the guaranteed operating time, in accordance with the specification for AE, the reduction in the radiation power should QRWEHPRUHWKDQ/RQJHYLW\WHVWVDQGFRQWLQXRXVRSHUDWLRQRI CVL show that the service life of sealed-off AEs on copper vapour is DWOHDVWK'XULQJWKLVSHULRGRIRSHUDWLRQRIWKH$(WKHJORZ of the buffer gas of neon does not practically change in them, but the power of the radiation decreases. (The gas glow is checked by a high-frequency device of the Teslo type.) The first testifies to the preservation of the purity of the gaseous medium, and, accordingly,

New Generation of Efficient Sealed-off Active Elements

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Fig. 3.35. The appearance of the sectional discharge channel of the laser AE */& .XORQ  DIWHU  KRXUV RI RSHUDWLRQ 1 ± WKH GLVFKDUJH FKDQQHO WXEH 2±FRQQHFWLQJVOHHYH3±FRQGHQVHU4±QHDUHOHFWURGHWXEH5±DOXPRSKRVSKDWH FHPHQW $3&  6 ± VHDOLQJ FHPHQW 7 ± PRO\EGHQXP ULQJ DQG ZLUH

the high efficiency of the three-step technology for degassing and cleaning devices, and the second is about reducing the specific power take-off and the concentration of copper vapour in the AM. Devices WKDWKDYHEHHQLQRSHUDWLRQIRUDORQJWLPH±K DUHXVXDOO\ analyzed for analysis of the state of its nodes and materials and their evaluation for reuse. A high-temperature partitioned discharge channel is usually retained by a solid node (Fig. 3.35), but can not be restored. Due to the strong sintering of the sealing cement (item 6), the ceramic channel is not disassembled into individual tubes (item 1) and bushings (item 2), which in turn does not allow replacement of the spent copper vapour generators for new ones. 2QO\WKHQHDUHOHFWURGHFHUDPLFWXEHVLWHP ZLWKRXWFDSDFLWRUV (item 3) can be reused. Molybdenum capacitors are in a state of HPEULWWOHPHQW 7KH WXQJVWHQ±EDULXP FDWKRGH DQG WKH PRO\EGHQXP anode are almost always suitable for reuse in new AEs since its VHUYLFH OLIH LV DW OHDVW  KRXUV 7KH RXWHU YDFXXPWLJKW PHWDO glass casing and the two end sections with optical windows, having a technological margin for the diameter of the welding of the metal cups, are suitable for two-three times repeated application. Hightemperature heat insulators: fibrous grade VKV-1 and powder grade T can be re-applied only after removal of the sintered areas, which PD\ FRQVWLWXWH ± RI WKH WRWDO PDVV

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Laser Precision Microprocessing of Materials P rad, kW

0

600 1200 1800 2400

t, h

Fig. 3.36. Dependences of the average radiation power of the CVL with the Kulon AE, PRGHO*/(RQWKHRSHUDWLQJWLPH1±ZLWKVWDQGDUGFRSSHUYDSRXUJHQHUDWRUV 2 ± ZLWK DQ LQFUHDVHG VXSSO\ RI FRSSHU LQ WKH H[WUHPH FRSSHU YDSRXU JHQHUDWRUV

Figure 3.36 shows the dependence of the average radiation power IRU WZR$(V .XORQ RI WKH */( PRGHO GLIIHULQJ LQ WKH UHVHUYH RI WKH FRSSHU ZRUNLQJ VXEVWDQFH ,Q WKH H[WUHPH FRSSHU YDSRXU generators there was no substance, and in the only central one half of WKHLQLWLDOPDVVUHPDLQHG)RUWKHH[WUHPHJHQHUDWRUVWKHFDOFXODWHG value of the service life (up to complete depletion of copper) is about KWKHFHQWUDORQH±K$WWKHVDPHWLPHWKHSDWKOHQJWK RIWKHGLIIXVLRQHVFDSHRIFRSSHUYDSRXUIRUWKHH[WUHPHJHQHUDWRUV GHWHUPLQHGE\WKHGLVWDQFHWRWKHFDSDFLWRUVLVPPIURPDVLQJOH FHQWUDO RQH  PP DW ERWK HQGV 7KHUHIRUH D PRUH LQWHQVLYH ORVV of copper vapour and earlier depletion of metallic copper from the H[WUHPH JHQHUDWRUV OHDGV LQ WKH SURFHVV RI RSHUDWLRQ WR D GHFUHDVH in the concentration of copper vapour in the AS and, accordingly, the radiation power. The latter is indicated, as already mentioned DERYHE\WKHIDOORIFXUYH)LJ LQWKHVHFWLRQRI± K :LWK D UXQWLPH RI PRUH WKDQ  K WKH UDGLDWLRQ SRZHU OHYHO is minimal, since the AE already operates in the regime with only one central generator, when the concentration of copper vapour in AM does not reach optimal values. The losses of radiation power from the dusting of the output windows does not have a noticeable HIIHFW RQ WKH FRXUVH RI FXUYH  VLQFH WKH\ FRQVWLWXWH DERXW  RI the total power. ,Q WKH $( .XORQ */( ZLWK D IROG LQFUHDVH LQ WKH FRSSHU UHVHUYHLQWKHH[WUHPHFRSSHUYDSRXUJHQHUDWRUVWKHUDGLDWLRQSRZHU as seen from curve 2 (Fig. 3.36), decreases monotonically and in  K GHFUHDVHV IURP  WR  : WR  OHYHO IURP WKH LQLWLDO value. A portion of the steep power drop on curve 2, as in the case of the AE with standard generators (curve 1), is not present. But it became also clear that even with a large reserve of the active substance, while maintaining the purity of the buffer gas of neon

New Generation of Efficient Sealed-off Active Elements

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DQG WKH FRQGLWLRQV RI H[FLWDWLRQ WKHUH LV VWLOO D GHFUHDVH LQ SRZHU albeit more delayed. This circumstance clearly indicates a decrease in the concentration of copper vapour in the AM and, correspondingly, the rate of evaporation from the surface of the molten copper in the generators during the operation of the AE. And at a time when the rate of evaporation of copper vapour from the generators becomes lower than the rate of vapour escape into the ‘cold’ ones, then a decrease in the radiation power becomes noticeable. This event XVXDOO\ RFFXUV ± KRXUV IURP WKH EHJLQQLQJ RI WKH RSHUDWLRQ of the AE (see curves 1 and 2). To determine the reasons for the decrease in the rate of evaporation of copper vapour in the sealed-off AEs during the long-term operation of CVL, an analysis of the composition of the surface of metallic copper in standard samples of generators with a molybdenum substrate was carried out with the help of a secondary LRQ PDVV VSHFWURPHWHU 060 VHH )LJ   DIWHU ZRUNLQJ IRU DQGKRXUV,QWKHPDVVVSHFWURPHWHUPHWKRGVZHUHXVHG to bombard the surface with a beam of Ar + ions with an energy of 5 keV (for knocking out ions) and quadrupole mass filtration. In this case, the surface of the samples was sprayed layer by layer to a depth of 56 nm. Based on the results obtained, the composition of the copper surface was evaluated. From the mass spectral data it follows that the surface of the remaining copper in the spent AE generators has practically an order of magnitude less pollution by carbon, QLWURJHQ DQG R[\JHQ WKDQ WKH RULJLQDO FRSSHU 0RE JUDGH  EHIRUH DVVHPEOLQJWKHGHYLFHVZKLFKH[FOXGHVWKHLULQIOXHQFHRQWKHFRSSHU YDSRXUSUHVVXUH7KHPDVVRIFDUERQZDVQLWURJHQ± R[\JHQ ±  ,Q WKH VSHFWUXP LQVLJQLILFDQW WUDFHV RI FXSURXV R[LGH&X22ZLWKDQRWLFHDEOHGHFRPSRVLWLRQWHPSHUDWXUHRQO\IURP ƒ&ZHUHIRXQG$WWKHVDPHWLPHGHVSLWHWKHORZVROXELOLW\RI molybdenum in copper, molybdenum is present in working copper ZLWK DQ RSHUDWLQJ WLPH RI  KRXUV ZLWK D SHUFHQWDJH FRQWHQW RI DERXWZLWKDQRSHUDWLQJWLPHRIKWR0RO\EGHQXP forms clusters in copper of various sizes, to microscopic (and probably nanoscale). The formation of molybdenum structures with D GHYHORSHG VXUIDFH LV FRQILUPHG E\ PLFURVFRSLF H[DPLQDWLRQ RI samples the copper of which is etched with nitric acid. Segregation of copper on a large total surface of molybdenum clusters increases the enthalpy (necessary energy) of evaporation of copper from the system as compared to pure copper. This phenomenon naturally leads to a decrease in the rate of evaporation of copper vapour from the

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Laser Precision Microprocessing of Materials 9

4

7

2

6

8

3

5

10

Fig. 3.37. 7KH GHVLJQ RI WKH VHDOHGRII VHOIKHDWLQJ$( .XORQ6S RI WKH SXOVHG CVL: 1±DVHFWLRQHGGLVFKDUJHFKDQQHO2±VSLUDOIURP:±5HZLUHZLWKDGLDPHWHU of 1 mm; 3±FRSSHUYDSRXUJHQHUDWRUV4±:±%DFDWKRGH5±PRO\EGHQXPDQRGH 6, 8 ± KHDW LQVXODWRUV 8 ± YDFXXPWLJKW VKHOO 9 ± HQG VHFWLRQ ZLWK DQ RSWLFDO window; 10 ± VFUHHQ WUDS

generators and their concentration in the AM and, as a consequence, to a decrease in the radiation power. In the future as a substrate material for copper vapour generators it is necessary to consider refractory rhenium (T m  ƒ&  DQG LWV DOOR\V ZLWK PRO\EGHQXP and tungsten, which have a more favourable combination of the physical and chemical properties in comparison with molybdenum. These materials are plastic, their heat resistance is higher than that RIPRO\EGHQXPDQGLVNHSWWRDWHPSHUDWXUHƒ&$WSUHVHQWWKH $( .XORQ */( ZLWK FRSSHU YDSRXU JHQHUDWRUV RQ D UKHQLXP VXEVWUDWH XQGHUJRHV UHVRXUFH WHVWV 7KH RSHUDWLQJ WLPH LV  K QR noticeable changes in the radiation power are observed. Design and parameters of the AE Kulon-20Sp with a spiral heater of the discharge channel. :LWK WKH SXUSRVH RI LQFUHDVLQJ the reliability of the power source and decreasing the readiness time RIWKHSXOVHG&9/WKHVHDOHGRII$(RQFRSSHUYDSRXU.XORQ6S ZLWK D VSLUDO GLVFKDUJH FKDQQHO KHDWHU >@ ZDV GHYHORSHG DQG H[SHULPHQWDOO\LQYHVWLJDWHGRQDODERUDWRU\WHVWVWDQG7KHGHVLJQRI WKH$(RIWKH.XORQ6SRIWKHSXOVHG&9/LVVKRZQLQ)LJ 7KHGLVFKDUJHFKDQQHOSRVLWLRQ RIWKH$(RIWKH.XORQ6S as in industrial AEs of the Kulon series, has a sectional construction > @ 7KH FKDQQHO FRQVLVWV RI ILYH FHUDPLF WXEHV ZLWK DQ LQQHU GLDPHWHURIPPDQGDQRXWHUGLDPHWHURIPPLQWHUFRQQHFWHG by ceramic bushings with an internal diameter of 26 mm and an RXWHU GLDPHWHU RI  PP 7KH FHUDPLF PDWHULDO LV DOXPLQXP R[LGH JUDGH$ $O 22 3  2Q WKH LQQHU VXUIDFH RI WKH FRQQHFWLQJ bushings there are four copper vapour generators (item 3) consisting of a cylindrical molybdenum substrate and an active copper substance (14 g each). The vacuum-tight shell (item 8) is cermet with glass HQG VHFWLRQV LWHP   LQ ZKLFK RSWLFDO ZLQGRZV IRU ODVHU UDGLDWLRQ

New Generation of Efficient Sealed-off Active Elements

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H[LW DUH ZHOGHG DW DQ DQJOH WR WKH RSWLFDO D[LV RI WKH$(7KH PDLQ part of the casing (item 8) is made of ceramics 22KhS which has an outer diameter of 72 mm, an inner diameter of 62 mm. Soldering of WKHPLGGOHVHDPRIDFHUDPLFF\OLQGHUZDVFDUULHGRXWZLWKD36U VROGHU ZLWK D PHOWLQJ SRLQW RI ƒ& 7KH VSDFH EHWZHHQ WKH KLJK temperature discharge channel (item 1) and the vacuum-tight shell (item 8) is filled with a finely dispersed powder heat insulator (item 6) of the T grade from Al 22 3 with the size of hollow microspheres RI±—PKDYLQJDORZWKHUPDOFRQGXFWLYLW\RI:PÂ. The widened metal ends of the shell are filled with heat insulation from kaolin ILEHULWHP RIJUDGH9.9$O 22 36L2 2) with ILEHUVL]HVȝPDQGWKHUPDOFRQGXFWLYLW\:PÂ. 7KH PD[LPXP RSHUDWLQJ WHPSHUDWXUH RI WKH WKHUPDO LQVXODWRU RI WKH 7 EUDQG LV ƒ& JUDGH9.9 ± ƒ& The spiral heater (item 2) is wound directly onto the discharge FKDQQHO 7KH VSLUDO KDV  WXUQV RI WXQJVWHQ±UKHQLXP :±5H  ZLUHPPLQGLDPHWHUJUDGH957KHHQGVRIWKHVSLUDOGXHWR argon-arc welding, have reliable electrical contact with the electrode QRGHV RI WKH $( 7KH UHVLVWDQFH RI WKH KHOL[ LQ WKH FROG VWDWH LV a2KPLQWKHVWDWHSUHKHDWHGWRƒ&LWLV2KP7KHDQQXODU FDWKRGHOLNHLQLQGXVWULDO$(VLVWXQJVWHQ±EDULXPRSHUDWHVLQWKH regime of auto-thermoemission at the localization of a pulsed arc discharge into a spot about 1 mm in size, the anode is molybdenum. The optical windows of the AE intended for output of laser generation Lr

Lm

LAE

Lf kV

Cf

L hc LATR Lf Cf

Fig. 3.38. 7KH EDVLF HOHFWULFDO FLUFXLW RI D KLJKYROWDJH SXOVHG SRZHU VRXUFH 7 ± KLJKYROWDJHSXOVHGK\GURJHQWK\UDWURQɌ*,+5±KLJKYROWDJHUHFWLILHU ±N9 N9±NLORYROWPHWHU L c±FKDUJHFKRNHL r±UHVRQDQWFKRNHC 1 C 2  Q)±VWRUDJHFDSDFLWRUVL m±QRQOLQHDUPDJQHWLFFKRNHC 3 Q)±VKDUSHQLQJ FDSDFLWRU /$( ± ODVHU DFWLYH HOHPHQW L hc ± KHDWLQJ FRLO RI WKH GLVFKDUJH FKDQQHO C f Q)±ILOWHUFDSDFLWRUL f ȝ+ILOWHUFKRNHA±DPPHWHU±$ C 4  Q)±VKXQWFDSDFLWRUT p±LVRODWLQJWUDQVIRUPHU9 /$75±ODERUDWRU\ autotransformer.

134

Laser Precision Microprocessing of Materials

DUH LQVWDOOHG DW DQ DQJOH RI ƒ WR WKH D[LV RI WKH GHYLFH DQG DUH SURWHFWHG IURP GXVWLQJ E\ VFUHHQV SRVLWLRQ  In the process of training AE, in its degassing in the mode of SXPSLQJ QHRQ WKH PD[LPXP VKHOO WHPSHUDWXUH ZDV ƒ& WKH GLVFKDUJH FKDQQHO ƒ& 7KHUHIRUH LQ WKH RSHUDWLQJ PRGH WKH WHPSHUDWXUHV GLG QRW H[FHHG WKH DERYH YDOXHV Figure 3.38 shows the principal circuit diagram of a high-voltage LPSXOVH SX\OVHG SRZHU VRXUFH > @ ZLWK D FLUFXLW IRU IHHGLQJ D spiral heater of the discharge channel of the AE. 7KH$(WHVWVZHUHFDUULHGRXWDWDQHRQEXIIHUJDVSUHVVXUHRI PP+J$WWKLVSUHVVXUHWKH35)RIWKHSXPSFXUUHQWSXOVHVRI N+] DQG WKH FRPELQHG SRZHU VXSSO\  N: IURP WKH ORZYROWDJH VSLUDO KHDWHU DQG  N: IURP WKH KLJKYROWDJH SXOVH PRGXODWRU WKH average radiation power with a planar-spherical resonator (R1 P R 2  ’  ZDV : ,Q WKLV PRGH WKH DPSOLWXGH RI WKH SXOVHV RI WKH GLVFKDUJH FXUUHQW ZDV  $ ZLWK WKH GXUDWLRQ RI LWV IURQW DQG WKH WRWDO GXUDWLRQ RI  DQG  QV UHVSHFWLYHO\ YDOXH RI WKH YROWDJH DPSOLWXGHN9 7KHVKHOOWHPSHUDWXUHGLGQRWH[FHHGƒ&7KHVH results were obtained on a test bench without the use of a reverse FRD[LDO FRQGXFWRU XQGHU FRQGLWLRQV RI IUHH FRQYHFWLRQ DQG ZLWKRXW DQ DQWLUHIOHFWLRQ FRDWLQJ RI WKH H[LW ZLQGRZV RI WKH$( ,WVKRXOGEHHPSKDVL]HGWKDWWKHXVHRIDQH[WHUQDOVSLUDOKHDWHURI the discharge channel allows to eliminate the danger of its destruction during the warm-up period by reducing the temperature difference EHWZHHQWKHH[WHUQDODQGLQWHUQDOZDOOVWRVKRUWHQWKHKHDWLQJWLPH of the AE, to substantially increase the service life of the pulsed hydrogen thyratron (switch) and the reliability of the high voltage 3RZHUVRXUFHDVDZKROHIRUDFFRXQWIRUWKHGHFUHDVHLQWKHIUDFWLRQ of power invested in the gas discharge of the AE. Basic parameters and characteristics of industrial sealed-off AE of the Kristall series. The main parameters of a new generation of industrial sealed-off self-heating AEs of the Kristall series of WKH SXOVHG &9/V DUH JLYHQ LQ 7DEOH  >    @ They are obtained and optimized with a power source, whose highvoltage pulse modulator is made according to a capacitive voltage doubling scheme with a link of magnetic compression of nanosecond current pulses and an anode reactor (Fig. 3.27 d). Such a version RI WKH WK\UDWURQ ,3 WRGD\ LV WKH PRVW UHOLDEOH DQG HIIHFWLYH VRXUFH RI H[FLWDWLRQ RI $8 RQ FRSSHU YDSRXU $V D KLJKYROWDJH SXOVH commutator in a modulator, a powerful hydrogen thyratron of the W\SH 7*,F ZLWK ZDWHU FRROLQJ RI WKH GHYHORSPHQW RI WKH

Model /7&X D

    ± ± ± ± 1:1 ±

    ± ± ± ± 1:1 ±

1:1 ±

± ±

1:1 ±

±

   32 32     ± ± ±

*/ &

Radiation wavelength, nm 3UHVVXUHRIWKHEXIIHUJDV1HPP+J Diameter of the discharge channel, mm Length of the discharge channel, mm Volume of active medium, cm3 3XOVHUHSHWLWLRQIUHTXHQF\35)  optimum operating range, kHz $YHUDJHUDGLDWLRQSRZHUZLWKRSWLPDO53) : oscillator mode DPSOL¿HUPRGH Ratio of radiation powers * Duration of radiation pulses, ns

*/ % Copper vapour

*/ $

Laser environment

3DUDPHWHU

1:1 35

1:1 35

± 117

±

± ±

 45  

LT&X

 45  

LT75Cu

Table 3.4 The main parameters of the new generation of industrial sealed-off self-heating AE of the Kristall series

± ±

±±

627.8     ± ±

*ROG vapour

*/ '

New Generation of Efficient Sealed-off Active Elements 135

*P radȜ QP P radȜ QP 

Minimum (guaranteed) operating time, h Service life not less than, h

Readiness time (at optimum power consumption), min





5



±

! 

±

±

3RZHUFRQVXPHGIURPWKHUHFWL¿HU,3N:

3 ±

4

Divergence of radiation with a telescopic unstable resonator, mrad

Divergence of radiation with a plane resonator, mrad

Table 3.4



5.7

4

5





! 



6.6

±

6

! 



± 3.5



4

136

Laser Precision Microprocessing of Materials

New Generation of Efficient Sealed-off Active Elements

137

,VWRN 133 >@ LV XVHG 7KH FDSDFLW\ RI WKH VWRUDJH FDSDFLWRU LV 2C      S) WKH VKDUSHQLQJ FDSDFLWRU LV C ob   S) $ OLQN RI PDJQHWLF FRPSUHVVLRQ FRROHG E\ ZDWHU LQFOXGHV ± IHUULWHULQJVRIWKH010EUDQGZLWKGLPHQVLRQVRIîî mm. The AEs of the Kristall series the volume of the active medium RI ZKLFK LV ± RUGHUV RI PDJQLWXGH JUHDWHU WKDQ WKDW RI WKH$( RI the Kulon series, when using an effective scheme of voltage doubling and magnetic compression of pulses have almost twice the radiation power than in the case of a direct scheme of the power source (Fig. 3.27 a). The optimization of the new generation of sealed-off AEs RI WKH .ULVWDOO VHULHV RI WKH SXOVHG &9/ WR DFKLHYH WKH PD[LPXP operating efficiency and power of radiation was carried out using, ILUVW RI DOO WKH UHVXOWV RI XQLTXH H[SHULPHQWDO VWXGLHV > @ 7KH PD[LPXP YDOXHV RI WKH DYHUDJH UDGLDWLRQ SRZHU VKRZQ LQ 7DEOHFRUUHVSRQGWRWKH$(ZLWKWKHDQWLUHIOHFWLQJH[LWZLQGRZV (transmittance IJ  &XUUHQWO\WKH$(VRIWKH.ULVWDOOVHULHVDUH produced only with the antireflecting windows. The construction and manufacturing technology of the AE of */' RI WKH SXOVHG JROG YDSRXU ODVHU *9/  DUH LGHQWLFDO WR WKH*/$PRGHOIRUWKH&9/DQGGLIIHURQO\LQWKHFRPSRVLWLRQ of the active substance and, correspondingly, in the wavelengths of the radiation (see Table 3.4). The average radiation power of the Table 3.5. Comparison of power and efficiency of old and new industrial models of AEs of the Kristall series Model AE Kristall 3DUDPHWHU

*/

*/ $

VȺ0 FP3

*/ (

*/ %

VȺ0 FP3

*/ D32

*/ &

VAM FP3

Average radiation power LQJHQHUDWRUPRGH:

35

35

44

45

55

55

3RZHUFRQVXPHG IURPWKHUHFWL¿HU RIWKHSRZHUVRXUFHN:

3.6



4.4

3.6

5.5

4.6

1

1.17

1

1.2

1

1.2

3UDFWLFDO HI¿FLHQF\

138

Laser Precision Microprocessing of Materials

$( */' LV ± : WKH JXDUDQWHHG UXQQLQJ WLPH LV  KRXUV ZKLFK LV  WLPHV OHVV WKDQ WKDW RI WKH */$ */% DQG */ & PRGHOV 7KH ODWWHU LV H[SODLQHG E\ WKH IDFW WKDW WKH RSWLPDO working temperature of the discharge channel of AE on gold vapour (T chanaƒ& LV±ƒ&KLJKHUWKDQWKDWRIWKH$(RQFRSSHU YDSRXU $SSOLFDWLRQ LQ WKH $( .ULVWDOO */% DQG */& RI gold as an active substance allows to raise the level of radiation SRZHU DW D ZDYHOHQJWK Ȝ   QP WR : Comparative analysis of the efficiency of old and new models of AE of the Kristall series. The efficiency of old and new models of the AE of the Kristall series was estimated from the values of the average radiation power, the power consumed by the power source of the rectifier, and the practical efficiency in the optimum operating modes. The practical efficiency is defined as the ratio of the output radiation power to the power consumed by the rectifier of the power source. From the comparative Table 3.5 it follows that for the same values of the radiation power, the power consumption of the AE of WKH .ULVWDOO VHULHV RI WKH QHZ PRGHOV */$ */% DQG */ &LVDSSUR[LPDWHO\WLPHVVPDOOHUDQGWKHSUDFWLFDOHIILFLHQF\ LVFRUUHVSRQGLQJO\KLJKHUWKDQIRUWKHROG*/*/(DQG*/ (7KHGHFUHDVHLQWKHSRZHUFRQVXPSWLRQRIWKHSRZHUVRXUFH led to an increase in the service life of high-voltage pulse thyratrons ZKLFK IRU D SRZHUIXO 7*, LV QRW OHVV WKDQ  KRXUV The service life of new AE models is determined practically only by the reserve of the active substance in copper vapour generators, the operating temperature of the discharge channel and buffer gas pressure neon, since the main causes of the destruction of the ceramic discharge channel are eliminated, overlapping of the channel aperture by drops of condensing copper, dusting of the output windows with copper vapour, electrode erosion products and other particles. At the same time, the minimum operating time of the instruments increased IURPWRKHQVXULQJKLJKTXDOLW\RIWKHRXWSXWUDGLDWLRQDQG reproducibility of the parameters. This level of basic parameters for industrial sealed-off AEs of the pulsed CVL is quite acceptable for wide application in modern technological equipment. Influence of hydrogen on efficiency and power of radiation of industrial sealed-off self-heating AEs of the Kristall series. 2QH of the ways to increase the radiation power and the efficiency of pulsed CVL is the addition of molecular hydrogen to the gas medium RI $( >±@ ,Q >@ LW ZDV VKRZQ IRU WKH ILUVW WLPH WKDW WKH addition of molecular hydrogen to the neon buffer gas significantly

New Generation of Efficient Sealed-off Active Elements

139

LQFUHDVHV WKH HIILFLHQF\ RI WKH &9/ XS WR   ,Q >@ WKH PDLQ H[SHULPHQWDO DQG WKHRUHWLFDO VWXGLHV DUH FRQVLGHUHG LQ ZKLFK WKH influence of hydrogen on the operating mode of CVL and on its output characteristics is determined. Depending on the geometric dimensions of the discharge channel AE (D chan   ± FP L chan ±FP SXULW\RIWKHDFWLYHPHGLXPEXIIHUJDVSUHVVXUH (pNe ±PP+J DQG35)±N+] WKHRSWLPDODPRXQW RI K\GURJHQ DGGHG LV ± +\GURJHQ DGGLWLYHV LQFUHDVH PRUH significantly increase the efficiency of the CVL than the power of its radiation, as the electrical matching between the AE and the pumping modulator improves. The temperature of the discharge FKDQQHO LV LQFUHDVHG E\ ±ƒ& 7KH LQFUHDVH LQ WKH DPSOLWXGH RI WKH YROWDJH SXOVHV DW WKH GLVFKDUJH JDS RI WKH$( UHDFKHV  and the amplitude of the current pulses, on the contrary, decreases, and the duration of the radiation pulse increases. The latter, when using a telescopic unstable resonator, leads to an increase in the UDGLDWLRQ SRZHU LQ D EHDP RI GLIIUDFWLRQ TXDOLW\ 7KH RSWLPDO 35) FRUUHVSRQGLQJWRWKHPD[LPXPDYHUDJHUDGLDWLRQSRZHULVPRYHGWR the region of higher frequencies. 7KH DXWKRUV >@ H[SODLQ WKH LQFUHDVH LQ WKH HIILFLHQF\ DQG power of the laser radiation with addition of molecular hydrogen, in particular, by an intensive decrease in the electron temperature in the afterglow period due to elastic and inelastic collisions. ‘Chilled’ electrons speed up the recombination of electrons and ions, which reduces the pre-pulse concentration of the electrons. In this case, in the period between the current pulses, a faster and full transition of copper atoms to the ground state occurs and the pulse voltage applied to the AE increases. (DUOLHU H[SHULPHQWDO VWXGLHV RI WKH HIIHFW RI K\GURJHQ RQ WKH HIILFLHQF\RIWKHVHDOHGRIIVHOIKHDWLQJ$(VRIWKH.ULVWDOOVHULHV*/  */( DQG */( ZHUH FRQVLGHUHG ,W ZDV HVWDEOLVKHG WKDWWKHDGGLWLRQRIK\GURJHQWRDSDUWLDOSUHVVXUHRIPP+JLQWR the active medium (neon pressure p Ne ±PP+J OHDGVWRDQ LQFUHDVHLQWKHUDGLDWLRQSRZHUE\±WLPHV+HUHWKHLQIOXHQFH of hydrogen additives on the operation of new models of AE on WKH FRSSHU YDSRXU PRGHOV */$ .ULVWDOO /7&X  */% .ULVWDOO/7&X DQG*/&.ULVWDOO/7&X DWWKHSUHVVXUHV RI WKH QHRQ EXIIHU JDV ZDV VWXGLHG VHH7DEOH   >@ 7KH ZRUNLQJ SUHVVXUH RI QHRQ LQ WKH$( RI */$ LV  PP +J */% ±  PP +J */& ±  PP +J +LJK SXULW\ QHRQ ZDV XVHG ZLWK D YROXPH IUDFWLRQ RI  LPSXULWLHV  Â

140

Laser Precision Microprocessing of Materials

 í  +H   Â  í  2 2   í  1 2   í  + 2   í  &+ 4  í&2 2Â í + 22 K\GURJHQRIVSHFWUDOSXULW\ZLWKD YROXPH IUDFWLRQ RI  LPSXULWLHV  Â  í  2 2 + Ar) + 2 Â  í  1 2   Â  í  &+ 4   Â  í  + 22  7KH K\GURJHQ ZDV injected into the Kristall AE after finishing training for its degassing and purification with hydrogen and then filling it with pure neon to operating pressure and warming up to an operating temperature a ƒ&  )LJXUHVKRZVWKHGHSHQGHQFHRIWKHDYHUDJHUDGLDWLRQSRZHU RIWKH$(*/%/7&X.ULVWDOO RIWKH&9/ZLWKDQHIIHFWLYH thyratron power source (Fig. 3.27 e DWN+]IURPWKHK\GURJHQ SUHVVXUH DGGHG WR WKH QHRQ EXIIHU JDV 7KH H[LW ZLQGRZV RI WKH AE did not have an antireflection coating. At the same time, the amplitude of the voltage pulses was 28.4 kV, and its duration on WKHEDVHZDVQVIRUFXUUHQWSXOVHVWKHFRUUHVSRQGLQJYDOXHVDUH  N$ DQG  QV 7KH K\GURJHQ JDV ZDV XVXDOO\ LQWURGXFHG IURP WKH FDWKRGH VLGH RI WKH$( WKURXJK D JODVV H[KDXVW WXEH LQ WKH HQG section, its amount being controlled by a U-shaped oil manometer. In RUGHUWRDFFHOHUDWHWKHSURFHVVRIPL[LQJK\GURJHQZLWKQHRQLQWKH $(WKHRXWSXWYDOYHRIWKHJODVVH[KDXVWWXEHZDVRSHQHGIURPWKH anode side and the gas was evacuated from the device until the initial pressure was established. In another case, the system was left for ±KRXUVWKLVWLPHZDVVXIILFLHQWIRUFRPSOHWHPL[LQJRIWKHJDV PL[WXUH,QWKHDEVHQFHRIK\GURJHQDGGLWLYHVWKHDYHUDJHSRZHURI P rad, W

0

4(2)

8(4) PH 2 ,

12(6)

mm MM. pT.Hg CT. (%) (%)

Fig. 3.39. Dependence of the average radiation power of the CVL with the AE .ULVWDOO RI WKH */% PRGHO ZLWK DQ HIIHFWLYH WK\UDWURQ SRZHU VRXUFH ZLWK D 35) RI  N+] RQ WKH K\GURJHQ SDUWLDO SUHVVXUH WKH YDOXH LQ WKH SDUHQWKHVHV LV the percentage of hydrogen).

New Generation of Efficient Sealed-off Active Elements

141

0.6 kA 23 kV

28.4 kV

0.4 kA

50 ns

180 mm Hg

a

150 mm Hg

a

Fig. 3.40. The oscillograms of the pulses of voltage (1), current (2), and radiation   RI ODVHU$( */$ /7&X .ULVWDOO  a  DQG */& /7&X .ULVWDOO  E  DW 35) RI  N+]

WKH$(UDGLDWLRQZDVDERXW:DWWKHRSWLPXPSRZHUFRQVXPSWLRQ P H[W   N: HIILFLHQF\   7KH PD[LPXP UDGLDWLRQ SRZHU was achieved at the partial pressure of p H2  ± PP +J  ± RI WKH JDV PL[WXUH SUHVVXUH  DQG ZDV ± : VHH )LJ   at a power consumption of P rect   N: HIILFLHQF\   7KH WHPSHUDWXUH RI WKH GLVFKDUJH FKDQQHO LQFUHDVHG IURP DERXW ƒ WR ƒ& 7KXV WKH DGGLWLRQ RI SXUH K\GURJHQ WR WKH */% led to an increase in the radiation power by 1.4 times (from 27 to :  SUDFWLFDO HIILFLHQF\ E\  WLPHV DQG WKH GLVFKDUJH FKDQQHO WHPSHUDWXUH E\ ƒ& 7KH HIILFLHQF\ LV LQFUHDVLQJ PRUH QRWLFHDEO\ WKDQ WKH UDGLDWLRQ SRZHU ZKLFK LV H[SODLQHG E\ WKH GHFUHDVH LQ WKH SRZHU FRQVXPSWLRQ IURP  WR  N: 7KDW LV WKH DGGLWLRQ of hydrogen leads to an improvement in the matching of AE with elements of the pump circuit (first of all, losses in the thyratron DUH UHGXFHG  $SSUR[LPDWHO\ WKH VDPH FKDQJHV ZHUH GHWHFWHG LQ the characteristics of CVL with the addition of hydrogen to the gas HQYLURQPHQW RI WKH $( */$ .ULVWDOO /7&X  DQG */& .ULVWDOO /7&X  7KH RVFLOORJUDPV RI WKH YROWDJH SXOVHV DQG GLVFKDUJHFXUUHQWIRUWKHVH$(DUHVKRZQLQ)LJ>±@ 7KH UDGLDWLRQ SRZHU RI WKH $( */$ LQFUHDVHV IURP  WR  :LHE\WLPHVWKHSUDFWLFDOHIILFLHQF\±IURPWR LHWLPHVIRUWKH$/*/&±IURPWR:WLPHV  DQGIURPWRWLPHV UHVSHFWLYHO\IURPZKLFKLWFDQ be concluded that with an increase in the diameter of the discharge

Laser Precision Microprocessing of Materials

142

P rad, W 40 20

0

400

800

1200

1600

2000

2400

2800 t, h

Fig. 3.41. Dependence of the average radiation power of CVL with AE Kristall LT&X*/&ZLWKDQHIIHFWLYHWK\UDWURQSRZHUVRXUFHRQWKHWLPHRIRSHUDWLQJ The asterisks mark the times at which the neon was pumped through the AE.

channel of the AE, the efficiency of the hydrogen additive increases. It should also be noted that the addition of hydrogen leads to an LQFUHDVHLQWKHUDGLDWLRQSRZHURQWKHJUHHQOLQHWRDJUHDWHUH[WHQW DQGLQWKHWRWDOGXUDWLRQRIWKHUDGLDWLRQSXOVHV)RUH[DPSOHZKHQ XVLQJ$/ */% ZLWKRXW WKH DGGLWLRQ RI K\GURJHQ WKH SRZHU RI HPLVVLRQ RQ WKH JUHHQ DQG \HOORZ OLQHV LV DSSUR[LPDWHO\ WKH VDPH and at the optimal hydrogen content the power of the emission on WKH JUHHQ OLQH ZDV  RI WKH WRWDO SRZHU RQ \HOORZ ±  )LJXUH  VKRZV WKH UHVXOWV RI WHVWV RI$( */& /7&X Kristall) with hydrogen additives with a partial pressure of 12 mm +J IRU  KRXUV LQ WKH VHDOHGRII PRGH QHRQ SUHVVXUH p Ne   PP +J H[LW ZLQGRZV RI WKH$( ± FODULILHG  $W WKH LQLWLDO PRPHQW WKH UDGLDWLRQ SRZHU ZDV ± : $IWHU  KRXUV RI RSHUDWLRQ WKH SRZHU RI WKH$( GHFUHDVHG E\  DQG therefore through it a slow pumping (in the operating mode) of pure QHRQ ZDV SHUIRUPHG WR UHPRYH H[FHVV K\GURJHQ 0RVW OLNHO\ DIWHU the regime of AE reduction by hydrogen, some hydrogen remained on its elements and at high operating temperatures it began to be released. The same technological procedure had to be done after KRXUVRIRSHUDWLQJWLPH,QWKHSHULRGIURPWRKRXUVRI operating time, a monotonic decrease in the radiation power from 52 WR:WRRNSODFHZKLFKFDQEHH[SODLQHGE\WKHVORZLQFUHDVHLQ the concentration of hydrogen in the active medium. Then the power VORZO\LQFUHDVHGDQGDWKRXUVWKHRSHUDWLQJWLPHUHDFKHG: This may be due to the subsequent slow decrease in the concentration of hydrogen in the active medium due to the prevailing processes of its absorption. Estimates show that the reserve of the active substance in copper vapour generators is sufficient to ensure the effective

New Generation of Efficient Sealed-off Active Elements

143

P rad, W

0

1(0,5)

2(1)

3(1 ,5) 4(2)

mm Hg (%) Fig. 3.42. 'HSHQGHQFHRIWKHDYHUDJHUDGLDWLRQSRZHURIWKH&9/ZLWKWKH/7&X .ULVWDOO$(WKH/7%PRGHODQGWKHODPSSRZHUVRXUFHRQWKHK\GURJHQSDUWLDO SUHVVXUHDWN+]35)YDOXHVLQWKHSDUHQWKHVHVDUHWKHSHUFHQWDJHRIK\GURJHQ 

RSHUDWLRQRI$(IRUPRUHWKDQKRXUV:LWKWKHFRQWLQXDWLRQRI WKH$(WHVWVWRKWKHUDGLDWLRQSRZHUZDVDOUHDG\Prad : The dependence of the radiation power on the addition of hydrogen has a more pronounced character in the case of a lamp power source (Fig. 3.27 b) than for a thyratron (Fig. 3.27 e :KHQ XVLQJWKH*/%$(WKHPD[LPXPUDGLDWLRQSRZHUZDVDFKLHYHG when p H2   PP +J DQG ZDV  : DW WKH 35)   N+] DQG P rect   N: )LJ   At partial pressures of hydrogen above 2 mm Hg the power falls off rather sharply. In the absence of hydrogen, the radiation power was equal to P   : DW D SRZHU FRQVXPSWLRQ RI  N: 7KH addition of hydrogen led to an increase in radiation power 1.5 times IURP  WR  :  SUDFWLFDO HIILFLHQF\  WLPHV IURP  WR   SRZHU FRQVXPSWLRQ  WLPHV IURP  WR  N:  WKH WHPSHUDWXUHRIWKHGLVFKDUJHFKDQQHOE\ƒ&IURPWRƒ&  If with the thyratron power supply, the addition of hydrogen causes an increase in efficiency greater than the increase in radiation SRZHUGXHWRDGHFUHDVHLQWKHSRZHUFRQVXPSWLRQE\ WKHQLQ the case of the lamp power source, on the contrary, a greater increase in the radiation power is detected (the power consumption increased E\ 7KHVHIHDWXUHVZKHQXVLQJWKHODPSSRZHUVRXUFHFDQEH H[SODLQHG RQO\ E\ VKRUWHU JHQHUDWHG FXUUHQW SXOVHV Figure 3.43 shows the dependence of the average radiation power RI WKH $( */% /7&X .ULVWDOO  RQ WKH 35) LQ WKH DEVHQFH of an additive and with the addition of hydrogen (p H2   PP +J  Before recording of the curves preliminary purification (flushing) of the AE with hydrogen was carried out, which led to an increase in

144

Laser Precision Microprocessing of Materials P rad, W 44 40 36

32

13

11

9

PRF, kHz

Fig. 3.43. Dependence of the average radiation power of CVL with AE Kristall /7&X*/%DQGWKHODPSSRZHUVRXUFHRQWKHWKH35)ZLWKRXWDGGLWLYH1) and with the addition of hydrogen at p H    PP +J 2). 2

21 kV

20 ns

Fig. 3.44. The oscillograms of the voltage pulses (1) and the current (2) of the CVL ZLWK WKH $( .ULVWDOO /7&X */% DQG WKH ODPS SRZHU VRXUFH DW  N+] 35) DQG p Ne    PP +J p H    PP +J 2

WKH UDGLDWLRQ SRZHU E\ DSSUR[LPDWHO\  7KLV LV PRVW OLNHO\ GXH WR WKH UHGXFWLRQ RI FRSSHU R[LGH &X2  LQ WKH QHDUVXUIDFH OD\HUV RI WKH FRSSHU YDSRXU JHQHUDWRUV 7KH R[LGH UHGXFHV WKH UDWH RI evaporation of copper in the generators, since it begins to decompose VLJQLILFDQWO\ RQO\ DW D WHPSHUDWXUH RI DERXW ƒ& >@ ,Q WKH absence of hydrogen, the radiation power decreased from 37 to  : ZLWK DQ LQFUHDVH LQ WKH 35) IURP  WR  N+] DQG ZLWK WKH K\GURJHQ DGGLWLRQ LW ILUVW LQFUHDVHG IURP  WR  : DW  kHz), then it slowly decreased (i.e., the addition of hydrogen to the &9/ JDV PL[WXUH OHDGV WR DQ LQFUHDVH LQ WKH RSWLPDO 35) :LWKDQ RSWLPXP  N+] 35) WKH DPSOLWXGH RI WKH YROWDJH SXOVH ZDV  N9WKHFXUUHQWLV$DQGWKHGXUDWLRQRIWKHOHDGLQJHGJHRIWKH current pulses is 25 ns (Figure 3.44). To determine the rate of hydrogen escape from the active gaseous PHGLXP RI WKH VHOIKHDWLQJ$( */% /7&X .ULVWDOO  ZLWK D lamp power source, the dependence of the radiation power on the time of operating at the optimum hydrogen pressures was obtained

New Generation of Efficient Sealed-off Active Elements

145

P rad, W 48 40

32 24

3 0

400

800

1200 1600 t, h

Fig. 3.45. Dependence of the average radiation power of CVL with AE Kristall LT&X*/%DQGODPSSRZHUDWN+]35)RQWKHRSHUDWLQJWLPH7KHYDOXH RIWKHSDUWLDOSUHVVXUHRIK\GURJHQPP+J LVLQGLFDWHGQH[WWRWKHFRUUHVSRQGLQJ points of the graph.

)LJ   7KH WHVWV ZHUH FDUULHG RXW DW  N+] 35) %HIRUH starting the tests, hydrogen was introduced into the AE to a partial SUHVVXUH RI ± PP +J DW ZKLFK WKH UDGLDWLRQ SRZHU UHDFKHG : Since the optimum value of the hydrogen pressure with a lampPRXQWHGSRZHUVRXUFHZDVPP+JWKHUDGLDWLRQSRZHUZLWKLQ KRXUV  LQFUHDVHG WR  : DQG WKHQ GXULQJ WKH QH[W  KRXUV LW GHFUHDVHGWR:$WWKLVSRLQWt K K\GURJHQZDVLQMHFWHG into the AE (pHe PP+J DQGDIWHUKRXUVWKHUDGLDWLRQSRZHU LQFUHDVHG WR  : DQG WKHQ GHFUHDVHG WR  : IRU WKH QH[W  hours. At the point t   K K\GURJHQ ZDV DJDLQ DOORZHG WR UHDFK pHe PP+J DQGWKHSRZHUGURSSHGWR:$IWHUKDIWHU this (t K WKHUDGLDWLRQSRZHUZDVUHVWRUHGWR:DQGDIWHU DQRWKHU  K t   K  LW GURSSHG WR :$IWHU WKH DGGLWLRQ of a new portion of hydrogen (pHe PP+J WKHFRPSOHWHHVFDSH of hydrogen was most likely to occur at the time t   K ZKHQ WKH SRZHU EHFDPH : $Q DSSUR[LPDWH K\GURJHQ IORZ ZDV HVWLPDWHG IURP WKH DQDO\VLV RIWKHH[SHULPHQWWDNLQJLQWRDFFRXQWSRVVLEOHHUURUVLQGHWHUPLQLQJ the pressure in the processes of hydrogen inlet and evacuation; the pressure p He  ± PP +J LV VXIILFLHQW WR SURYLGH  KRXUV RI RSHUDWLRQ $ IXUWKHU GHFUHDVH LQ WKH UDGLDWLRQ SRZHU DIWHU  K LV GXH WR WKH GHSOHWLRQ RI WKH FRSSHU UHVHUYH LQ WKH H[WUHPH HQG  copper vapour generators. Therefore, in order to ensure that the WLPH RI JXDUDQWHHG RSHUDWLQJ WLPH H[FHHGV  K LW LV QHFHVVDU\ WR LQFUHDVH WKH PDVV RI FRSSHU LQ WKH H[WUHPH JHQHUDWRUV E\ DW OHDVW  'XULQJ WKH WRWDO RSHUDWLQJ WLPH RI WKH $( t   K

146

Laser Precision Microprocessing of Materials P rad, W

200

400

600 mm Hg (%)

Fig. 3.46. 7KHGHSHQGHQFHRIWKHDYHUDJHUDGLDWLRQSRZHURIWKH$(*/$/7 &X .ULVWDOO  1  */% /7&8 .ULVWDOO  2  DQG */& /7&X  3) ZLWK WKH WK\UDWURQ SRZHU VRXUFH RQ QHRQ SUHVVXUH DW  N+] 35)

DSSUR[LPDWHO\  VZLWFKLQJ F\FOHV ZHUH PDGH$W WKH VDPH WLPH the output windows of the AE remained clean, and, as the control check showed, their transmittance was practically unchanged. The aperture of the discharge channel also remains unopened. Dependence of the radiation power of the Kristall AE on the pressure of the neon buffer gas. Figure 3.46 shows the dependence of the average radiation power of the Kristall AE on the pressure RI WKH QHRQ EXIIHU JDV ZLWK WKH H[HFXWLRQ RI WKH SXPS PRGXODWRU according to the capacitive voltage doubling scheme with a magnetic compression link (Fig. 3.27 e). :KHQ WKH SUHVVXUH YDULHV IURP  WR  PP +J WKH UDGLDWLRQ SRZHU RI WKH $( */$ /7&X .ULVWDOO  FXUYH 1) decreased IURP  WR  : E\   */% /7&X .ULVWDOO  (curve 2  ± IURP  XS WR  : E\   */& /7&X Kristall) (curve 3  ± IURP  WR  : E\   7KH GHFUHDVH in the total radiation power is primarily due to the reduction in SRZHURQWKHJUHHQOLQHȜ ȝP GXHWRWKHLPSDLUPHQWRIWKH characteristics of the pump pulses (the duration of the leading edge and the total duration of the current pulses increase and its amplitude decreases). It also follows from the comparative analysis that when the discharge channel elongates and its diameter increases, i.e., when WKH YROXPH RI WKH DFWLYH PHGLXP LQFUHDVHV VHH FXUYHV ± LQ )LJ 3.46), the relative power drop becomes more pronounced. Therefore, as a rule, the AEs with large volumes have lower operating pressures. 7KXVLQWKH$(*/$WKHZRUNLQJSUHVVXUHLVPP+JDQG LQ WKH$( */& ±  PP +J VHH7DEOH 

New Generation of Efficient Sealed-off Active Elements

147

P rad, W

8

12

16

PRF, kHz

Fig. 3.47. 'HSHQGHQFHV RI WKH DYHUDJH UDGLDWLRQ SRZHU RI WKH $( */% /7 &X .ULVWDOO  1  DQG */& /7&8 .ULVWDOO  2) with the thyratron power VRXUFH RQ WKH 35)

Dependence of the radiation power of the Kristall AE on the pulse repetition frequency (PRF). The frequency characteristics of the Kristall AE (Fig. 3.47) were taken at the working neon pressures (see Table 3.4) with the same performance of the thyratron pump modulator of the power source (Fig. 3.27 d). :LWK DQ LQFUHDVH LQ WKH 35) IURP  WR  N+] WKH DYHUDJH UDGLDWLRQ SRZHU RI WKH $( */% /7&X .ULVWDOO  GHFUHDVHG VOLJKWO\±E\$(*/&/7&X.ULVWDOO ±E\,QWKH FDVHRIDUHGXFWLRQLQWKH35)ZLWKUHVSHFWWRWKHRSWLPDOYDOXH kHz), a relatively sharp decrease in the radiation power took place, ZKLFK LV H[SODLQHG E\ DQ LQFUHDVH LQ ORVVHV LQ WKH WK\UDWURQ GXH WR the increase in the anode voltage), a decrease in the fraction of the power that is used to heat the AE and, a decrease in the temperature RI WKH GLVFKDUJH FKDQQHO :LWK D GURS LQ WKH 35) IURP  WR  N+] WKH $( V SRZHU IHOO E\  :KHQ UHSODFLQJ WKH FDSDFLWDQFH of the storage capacitor 2C cap      S)   S) DQG the capacitance C sh   S) E\ C cap      S)   pF and C sh   S) DW  N+] UDGLDWLRQ SRZHU DQG HIILFLHQF\ VHH SRLQWV  DQG   ZHUUH DOPRVW WKH VDPH DV DW  N+] Efficiency of industrial sealed-off AE Kristall. For industrial VHDOHGRIIVHOIKHDWLQJ$(*/$/7&X.ULVWDOO ZLWKEOHDFKHG H[LW ZLQGRZV DW QHRQ ZRUNLQJ SUHVVXUH p Ne    PP +J  DQG the nominal power mode (see Table 3.4), the practical efficiency (determined from the power consumed from the power source UHFWLILHU  LQ WKH JHQHUDWRU PRGH LV DERXW  WKH HIILFLHQF\ RI WKH $(  LQ WKH SRZHU LQSXW  LV  IRU $( */% .ULVWDOO/7&X ZLWKpNe PP+J±WKHFRUUHVSRQGLQJYDOXHV

148

Laser Precision Microprocessing of Materials

Table 3.6. The power consumed from the rectifier power source, and the radiation SRZHU RI WKH &9/ ZLWK WKH$( */% .ULVWDOO /7&X  DQG WKH ODPS ,& AE serial number

PrectN:

Prad:



4.2

48



4.1

48



4.1

46



4.2

46



4.12

46



4.2

47



4.15

48

127 128

4.2

46



4.2

47



4.25

48

DUH  DQG  DQG IRU $( */& /7&X .ULVWDOO  ZLWK p Ne   PP +J  ±  DQG  7KH HIILFLHQF\ RI WKH $( LV about twice the practical efficiency, since in the elements of the FKDUJLQJ DQG GLVFKDUJH FLUFXLWV DSSUR[LPDWHO\ KDOI RI WKH SRZHU consumed by the rectifier is lost. For the AE Kristall CVLs it is also important to know the efficiency in the power amplifier mode, since these AEs are mainly XVHG LQ KLJKSRZHU ODVHU V\VWHPV VXFK DV WKH PDVWHU RVFLOODWRU ± SRZHUDPSOLILHU02±3$ DVWKH3$,QWKH&9/ZLWK$(*/$ /7&X.ULVWDOO WKHSUDFWLFDOHIILFLHQF\LQWKH3$PRGHLVDERXW   : N:  WKH HIILFLHQF\ RI WKH $( LWVHOI LV   WLPHV PRUH ZLWK$(*/%.ULVWDOO/7&X WKHFRUUHVSRQGLQJYDOXHV DUH:N: DQGDQGZLWK$(*/&/7&X .ULVWDOO ±:N: DQG7KHUDGLDWLRQSRZHUDQG HIILFLHQF\ RI WKH$( .ULVWDOO &9/ LQ WKH 3$ PRGH LV ± WLPHV KLJKHU WKDQ LQ WKH 02 UHJLPH Test results of the AE GL-205B (LT-40Cu Kristall) with a lamp power supply. 7KH UHVXOWV RI WHVWV RI WKH $( */% /7 &X .ULVWDOO  ZLWK D ODPS SRZHU VXSSO\ )LJ  b), developed E\$OWHN0RVFRZ DUHDQDO\]HG7KHSRZHUVRXUFHZLWKWKH*0,  $ PRGXODWRU SXOVH ODPS PDNHV LW SRVVLEOH WR JHQHUDWH SXPS FXUUHQWSXOVHVRI±QVGXUDWLRQLQDZLGHUDQJHRI35)DQGKDV KLJK RSHUDWLRQDO UHOLDELOLW\ ODPS OLIH LV DERXW  K  )RU WHVWLQJ

New Generation of Efficient Sealed-off Active Elements P rad, W

6

149

T chan, oC

5

1800

4 3

0,3

1700

2

0,2

1600

1

0,1

1500 3,4 3,6 3,8 4,0 4,2 P rect , kW

Fig. 3.48. The dependence of the average radiation power (1 RIWKH$(*/'/7 4AU Kristall) of the gold vapour laser, the temperature of its discharge channel (2), the practical efficiency (3), and the efficiency of the AE (4) on the power consumed E\ WKH SRZHU VRXUFH UHFWLILHU XQGHU QHRQ SUHVVXUH  PP +J DQG  N+] 35)

 VHULDO GHYLFHV IURP GLIIHUHQW ORWV ZHUH WDNHQ ZLWKRXW VSHFLDO VHOHFWLRQ 7KH UHVXOWV RI PHDVXUHPHQWV IRU WKH VDPH 35) ±  N+] ± DUH VXPPDUL]HG LQ7DEOH  The spread of the values of the nominal power consumed by the power source rectifier and the radiation power was minimal ǻP rect a : LH  ǻP rad a :  $ SODQHVSKHULFDO resonator with a radius of curvature of the ‘blind’ mirror R P was used. The power of the AE emission with the lamp power source  :  LV  WLPHV KLJKHU WKDQ ZLWK WKH WK\UDWURQ  :  8VLQJ WKH DQWLUHIOHFWLQJ RXWSXW ZLQGRZV WKH UDGLDWLRQ SRZHU ZDV a : ZLWKDSUDFWLFDOHIILFLHQF\RIDQGDQHIILFLHQF\RI7KH HIILFLHQF\ RI$( LQ WKH SRZHU DPSOLILHU PRGH UHDFKHG  Industrial sealed-off self-heating AE of the pulsed gold vapour laser. The basic designs and technology of training for the AE of D SXOVHG *9/ ZLWK D ZDYHOHQJWK RI Ȝ   ȝP DUH LQGXVWULDO pulsed CVLs, which use instead of the active substance of copper KLJK SXULW\ JROG =O  ZLWK WKH RSWLPDO WHPSHUDWXUH LQFUHDVLQJ E\ ±ƒ& XS WR ±ƒ&  )RU$( */) .XORQ /7 $X  ZLWK DQ DYHUDJH UDGLDWLRQ SRZHU RI QRW OHVV WKDQ  : WKH EDVLF GHVLJQ LV $( */' IRU $( */* .XORQ /7$X  ZLWK D SRZHU RI DW OHDVW  : ± */( VHH 7DEOH   IRU$( */'/7$X.ULVWDOO ZLWKDSRZHURIDWOHDVW:±*/$ VHH 7DEOH   7KH UDGLDWLRQ SRZHU RI WKH *9/ ZLWK WKH $( RI WKHVHPRGHOVLVDSSUR[LPDWHO\VL[WLPHVVPDOOHUWKDQWKHSRZHURID copper vapour laser. Figure 3.48 shows the dependence of the average

150

Laser Precision Microprocessing of Materials P rad, W 6

0,4

5

0,3

4

0,2 3

~ ~ ~ 150 300 450 600 750

mm Hg

Fig. 3.49. Dependences of the average radiation power (1  RI WKH $( */' /7$8 .ULVWDOO  RI WKH *9/ WKH SUDFWLFDO HIILFLHQF\ 2), and the efficiency of the AE (3  RQ WKH QHRQ SUHVVXUH DW  N+] 35)

P rad, W Efficiency, %

10

12

14

16

PRF, kHz

Fig. 3.50. Dependence of the average radiation power (1 RIWKH$(*/'/7 $8.ULVWDOO RIWKH*9/WKHSUDFWLFDOHIILFLHQF\2), and the efficiency of the AE (3  RQ 35) DW D QHRQ SUHVVXUH RI  PP +J

UDGLDWLRQSRZHURIWKH$(*/'RIWKH*9/WKHWHPSHUDWXUHRI its discharge channel of the practical efficiency and the efficiency of the AE on the power consumption. A power source with a highvoltage modulator was used which was made according to a scheme with a capacitive voltage doubling and a magnetic compression link (Fig. 3.27 d 7KH35)ZDVN+]WKHQHRQSUHVVXUHLQWKH$(ZDV PP+J7KHPD[LPXPUDGLDWLRQSRZHU±: ZDVDFKLHYHG DW WKH ZDOOV RI WKH GLVFKDUJH FKDQQHO DW ±ƒ& $ SODQH spherical resonator with a radius of curvature of the ‘blind’ mirror RI  P ZDV XVHG$W WKDW WKH SUDFWLFDO HIILFLHQF\ ZDV  DQG WKH HIILFLHQF\ RI WKH$( ZDV  :LWKWKHFKDQJHLQQHRQSUHVVXUHIURPWRPP+JDW N+] WKH UDGLDWLRQ SRZHU GHFUHDVHG IURP  WR  : FXUYH  LQ

New Generation of Efficient Sealed-off Active Elements

151

)LJ   WKH SUDFWLFDO HIILFLHQF\ ± IURP  WR  FXUYH   WKH HIILFLHQF\ RI $( ± IURP   WR  FXUYH   :LWK DQ LQFUHDVH LQ WKH 35) WKH GHFUHDVH LQ WKH UDGLDWLRQ SRZHU ZLWK LQFUHDVLQJ SUHVVXUH EHFRPHV PRUH DEUXSW )RU H[DPSOH DW  N+] WKH SRZHU ZDV UHGXFHG E\  $W D FRQVWDQW QHRQ SUHVVXUH p Ne   PP +J ZLWK DQ LQFUHDVH LQ IUHTXHQF\ IURP  WR  N+] WKH UDGLDWLRQ SRZHU GHFUHDVHG IURP  WR  : E\   FXUYH  LQ )LJ   7KH PD[LPXP UDGLDWLRQ SRZHU ZDV DWWDLQHG at a neon pressure p Ne    PP +J DQG WKH K\GURJHQ SUHVVXUH p He   PP +J DQG IRU RSWLPL]HG H[FLWDWLRQ FRQGLWLRQV ZDV : )RU$(*/)WKHQHRQSUHVVXUHFKDQJHIURPWRPP+J OHG WR D KDOYLQJ RI SRZHU IURP  WR :  7KHREWDLQHGUHVXOWVDOVRVKRZWKDWWKHSXOVHG*9/ZRUNVUDWKHU effectively at neon pressures close to the atmospheric pressure; under these conditions, the service life of the commercial sealed-off AE RQ JROG YDSRXU LV QRW OHVV WKDQ  K Dependences of the specific characteristics of industrial sealedoff AE of the CVLs on the volume of the active medium. The values presented in Tables 3.3 and 3.4 of the average radiation power for new models of industrial sealed-off self-heating AEs of the Kulon and Kristall series of the pulsed CVL were obtained under optimized pump modes with an effective thyratron power source (see Fig. 3.27 d :KHQFKRRVLQJWKHRSHUDWLQJSUHVVXUHRIWKHEXIIHUJDVQRWRQO\ the output power of the radiation was taken into account, but also the service life of the AE. For all new industrial sealed-off models of AEs on copper vapors, the minimum operating time is at least  K ZKLFK LV  WLPHV PRUH WKDQ WKDW RI WKH ILUVW ROG  LQGXVWULDO models. During the minimum operating time, in accordance with the specification for AE, the reduction in the average radiation power VKRXOG QRW H[FHHG  RI WKH QRPLQDO YDOXH Based on tabulated data, the dependences of the average and specific radiation power on the volume of the active medium (AM) have been constructed (Figs. 3.51 and 3.52), which are very important for evaluating the efficiency of sealed-off AEs. These dependences indicate possible ways to increase the power and efficiency of AE with large volumes of AM. Figure 3.51 shows WKHFXUYHVFRUUHVSRQGLQJWRWKHUDGLDWLRQSRZHUVLQWKH021) and 3$PRGH2 :KHQWKHYROXPHRIWKHDFWLYHPHGLXPYDULHVIURPVAM ~ 4.2 cm3IRU$(*/$.XORQ/76L WRVAMaFP3 for AE */&/76L.ULVWDOO WKHDYHUDJHUDGLDWLRQSRZHULQWKH02 PRGH LQFUHDVHG IURP  WR  : LQ WKH 3$ PRGH IURP  WR 

152

Laser Precision Microprocessing of Materials P rad, W

0

200

400

600

800 V AM, cm 3

VAc,

cM

3

Fig. 3.51. Dependence of the average radiation power of industrial sealed-off selfheating AE pulsed CVLs in the generator mode (1) and the power amplifier mode (2) on the volume of the active medium. P input AE W BT cm33 V VAAM c 'cM P rad W 80 BT 3 V AM' cm VAc cM 3

70

T, n

60

cmCM

–3 3

11

50

9

40

7

30

20

0,4

10

0,2

5 3

1 0

200

400

600

oc

1700 1650 1600 1550 1500 1450

800

Fig. 3.52. Dependence of the specific radiation power (P rad/V AM) (1) of the industrial sealed-off self-heating AE of the pulsed CVL, the specific power input to the AE (P input AE/V AM) (2), the temperature of the discharge channel (3) and the concentration of copper atoms (4) on the volume of the AM.

: ,I WKH YROXPH KDV LQFUHDVHG DSSUR[LPDWHO\  WLPHV   then the radiation power is only 44 times (75/1.7). Thus, the relative increase in power is about 4 times lower than the relative increase in the volume of the AM.

New Generation of Efficient Sealed-off Active Elements

153

The values of the radiation power during operation of the AE LQ WKH 3$ PRGH DQG WKH SRZHU LQSXW LQ WKH$( DUH XVHG WR SORW WKH curves reflecting the change in the specific radiation power (P input/ V AM) and the specific input power (P input/V AM) in dependence on the volume of the AM (Fig. 3.52). If the specific power in the AE of the */$ ZLWK V AM ~ 4.2 cm 3 (the power take-off from the volume XQLWRIWKH$0 LV:FP 3WKHQLQWKH$(*/&ZLWK V AM   FP 3  LW LV  :FP 3 , four times less, indicating that it is SRWHQWLDOO\SRVVLEOHWRDFKLHYHDWRWDOSRZHUWDNHRIIIURPD*/& GHYLFH /76L .ULVWDOO  WR  :  î    : 7R FRQILUP this possibility, the curves of the dependence of the temperature of the wall of the discharge channel where the vapour generators of the active substance copper are located (curve 3 in Fig. 3.52), and the concentration of copper atoms (curve 4) on the volume of the DFWLYH PHGLXP RI WKH$( ZDV LQYHVWLJDWHG 2Q WKH RQH KDQG FXUYH 2 indicates that in the active medium of AE with small volumes it is QHFHVVDU\ WR LQWURGXFH D VSHFLILF SRZHU RI WKH RUGHU RI ± : cm3LQRUGHUWRHQVXUHWKHRSWLPDOUHJLPH2QWKHRWKHUKDQGVXFKD KLJKOHYHORIVSHFLILFSRZHUIRU$(VZLWKODUJHYROXPHVLVH[FHVVLYH VLQFHHYHQDWDVSHFLILFSRZHUKLJKHUWKDQ±:FP3, the radiation power decreases because of the superheating of the active medium. ,Q$(*/$ZLWKVAM FP3, the operating temperature of the GLVFKDUJH FKDQQHO LV DERXW ƒ& ZKLFK FRUUHVSRQGV WR D FRSSHU FRQFHQWUDWLRQ RI DERXW  î  15 cm í DQG LQ */& ZLWK V AM  P rad W V AM cm 3 0,4 0,3 0,2 0,1

0

10

20

30

D chan, mm

Fig. 3.53. Dependence of the specific radiation power of industrial sealed-off selfheating AE pulsed CVLs on the diameter of the discharge channel of the AE at optimum operating temperatures.

154

Laser Precision Microprocessing of Materials P rad W V AM cm 3 0,4

1700

0,3 0,2

1650 °C 1630 °C

•

0,1 0

•

• 1675

oc

oc

1570 °C 2

4

6

8 N

–3 .1Ql 5, CM cm-3

Fig. 3.54. Dependence of the specific radiation power of industrial sealed-off selfheating AE of the pulsed CVLs on the concentration of copper atoms in the AM at optimum operating temperatures.

FP íWKHRSHUDWLQJWHPSHUDWXUHLVƒ&WKHFRQFHQWUDWLRQRI FRSSHUDWRPVLVî 15 cm í, that is, it is four times smaller (see curves 3 and 4). For additional analysis and evaluation of the performance of the industrial self-heating AEs of the CVL Figs. 3.53 and 3.54 show the dependences of the specific radiation power on the diameter of the discharge channel and on the concentration of copper vapour at optimal operating temperatures. The temperatures are indicated directly on the curve in Fig. 3.54. Tchan ƒ&±RSWLPXPZRUNLQJ WHPSHUDWXUH RI $( */& ZLWK D chan   PP T chan  ƒ& ± */% ZLWK D chan   PP T chan  ƒ& ± */( ZLWK D chan   PP T chan  ƒ&  */& ZLWK D chan   PP DQG T chan  ƒ&  */Ⱥ ZLWK D chan   PP As the diameter of the discharge increases, the probability of collision of copper atoms from the volume of the AM with the channel wall decreases and the rate of their reduction in the interimpulse period decreases from the state with a metastable level to the ground state. This process leads to an increase in the concentration of ‘metastable’ atoms in the AS and the need to reduce the optimal operating temperature of the channel (to avoid ‘overheating’ of the AM), which in turn leads to a decrease in the radiation power (Fig. 3.53). It turns out that the specific radiation power (ȡ) and the concentration of copper vapour (N) are related to each other by a practically direct proportional dependence (Fig. 3.52 b  GHWHUPLQHG E\ WKH H[SUHVVLRQ

New Generation of Efficient Sealed-off Active Elements

155

(IILFLHQF\  2

3

2 1

1

0

200

400

600

800

Fig. 3.55. Dependences of practical efficiency (1) and efficiency of AE (2) for industrial sealed-off AE of the pulsed CVL of the series Kulon and Kristall in the mode of the power amplifier on the volume of AM.

U

U·N / N  ,

where ȡ  is the power density at the vapour concentration N . How many times the concentration of copper vapour decreases, the power take-off per unit volume of AM decreases as much as again, and vice versa. 7KH IRUHJRLQJ DQDO\VLV RI H[SHULPHQWDO VWXGLHV FOHDUO\ LQGLFDWHV that in order to achieve high values of radiation power in CVL with ODUJHYROXPHVRIWKH$0WKH$(GHVLJQDQGWKHH[FLWDWLRQFRQGLWLRQV should be such as to ensure the optimum operating temperature of WKHGLVFKDUJHFKDQQHODWDOHYHORIƒ&ZLWKRXWRYHUKHDWLQJRIWKH AM, i.e. would create optimal conditions for inversion of populations in the AM at a vapour concentration copper n Cu a  16 cm í. 7R HVWLPDWH WKH PD[LPXP HIILFLHQF\ RI WKH LQGXVWULDO$( RI WKH CVL, curves were constructed for the dependence of the practical efficiency and efficiency of the AE on the volume of the AM (Fig.   :KHQ FDOFXODWLQJ WKH HIILFLHQF\ WKH YDOXHV RI WKH UDGLDWLRQ SRZHUV LQ WKH 3$ PRGH ZHUH XVHG This is especially important for the AE of the Kristall series, since WKH\DUHXVHGPDLQO\LQPXOWLPRGDO&9/6µ02±3$¶IRUWKHIRUPDWLRQ of powerful radiation beams. The radiation power of the Kristall AE LQ WKH 3$ PRGH LV DSSUR[LPDWHO\ ± WLPHV KLJKHU WKDQ LQ WKH 02 UHJLPH $QG DV FDQ EH VHHQ IURP WKH FRXUVH RI WKH FXUYHV LQ Fig. 3.55, with a change in the volume of the active medium from 4.2 cm 3 */$  WR  FP 3 */&  WKH SUDFWLFDO HIILFLHQF\ LQFUHDVHV IURP a WR a 1), and the efficiency of the AE

3DUWLDO pumping Sealed-off 3XPSLQJ system

Israel, Nuclear Research Center Istok England, 2[IRUG/DVHUV Istok

&9/

*/%.ULVWDOO/7 &X

$*/

*/'.XORQ/7 5Cu) Sealed-off

Sealed-off

Istok»

*/$.ULVWDOO/7 &X

AE type

Firm

AE model

14

42







±

6

±

5,2

±

DiamFreeter of the quency of discharge repetition channel, of pulses, mm kHz

±

< 1,5 : 1

< 1,7 : 1

1:1

± ± *** 45

!

1:1

3RZHU ratio*

“

±

Average radiation SRZHU:

 !

!

 ±

 !



±

 !

*XDUDQWHHG minimum (minimum) operating time of the AE, h

±±

±

±±

±

±±

3RZHUFRQsumed from WKHUHFWL¿HU power source and from the JULGN:

Table 3.7. The main parameters of industrial sealed CVL produced by the ,VWRN133DQGIRUHLJQDQDORJV

156

Laser Precision Microprocessing of Materials

Sealed-off Sealed-off 3XPSLQJ system Sealed-off Soldered

USA, Lasers Now 63(©Istok» England, 2[ford Lasers Bulgaria, “0DVKLQRH[port” USA, Lasers Now Israel, Nuclear Research Center

&9/:

*/'©.XORQ/7 &Xª

&X$

6&X/+

&9/:

&9/





25

25

14

14

15

±



±

±

±



±





±



±

5

7

±

±

±

2:1

< 1,5 : 1

1,4 : 1

±

± 

± !

± 

!

±

 !

± !

± 

* P radȜ QP P radȜ QP 

2SHUDWLQJWLPHIRURQHFRSSHUFKDUJH

:LWKDODPSSRZHUVRXUFH

Sealed-off

Bulgaria, 0DVKLQRH[SRUW

6&X/+

Table 3.7

± ±

± ±

± ±

± ±

± ±

± 1.2

± ±

New Generation of Efficient Sealed-off Active Elements 157

158

Laser Precision Microprocessing of Materials

IURPWR2) with a decrease in the specific power take-off IURP  WR :FP 3 (see curve 1 in Fig. 3.52). Comparative analysis of the effectiveness of industrial sealedoff self-heating CVLs with foreign analogues. To assess the effectiveness of domestic pulsed CVLs on the basis of industrial sealed-off self-heating AEs of the Kulon and Kristall series produced by the Istok Company, a comparative analysis of the main parameters with foreign analogues close in terms of radiation power was carried RXW)URPWKHGDWDJLYHQLWIROORZVWKDWWKHGRPHVWLF$(V*/$ /76L.ULVWDOO KDVWKHVDPHUDGLDWLRQSRZHUDVWKH,VUDHOLPRGHO &9/,IZHFRPSDUHWKHPRGHOVE\WKHGLDPHWHURIWKHGLVFKDUJH channel, we can assume that the volume of the active medium of WKH&9/LVDSSUR[LPDWHO\WZLFHDVODUJHDVWKDWRIWKH*/$ model (see Table 3.7) and the capacity of power take-off from a unit volume (efficiency) is lower by the same amount. The efficiency RI WKH (QJOLVK $*/ PRGHO LV DERXW IRXU WLPHV ORZHU E\ WKH VDPHFULWHULRQWKDQWKH*/%PRGHO/7&L.ULVWDOO )RUHLJQ DQDORJXHV ZLWK D SRZHU RI PRUH WKDQ  : ZRUN PDLQO\ LQ WKH continuous pumping of the buffer gas, i.e., the laser is equipped with DGGLWLRQDO VXSSRUW HOHPHQWV ,Q DGGLWLRQ WKH &9/ DQG $*/ models require a new portion of working copper at certain intervals  DQG  KRXUV UHVSHFWLYHO\  7KXV WKH GRPHVWLF GHYLFHV RI the Kristall series favourably differ from foreign ones with the same power level not only in efficiency, but also in that they have a sealed-off design of the AE. The latter increases the reliability of the laser as a whole and simplifies its operation. The devices of the Kulon series also have an advantage over the DQDORJXHVJLYHQ,QSDUWLFXODUWKHHIILFLHQF\RIWKH*/(PRGHO /76L.XORQ LVDERXWWZLFHWKHHIILFLHQF\RIWKH&9/:86$  DQG &9/ ,VUDHO  PRGHOV DQG WKUHH WLPHV WKH HIILFLHQF\ RI WKH &8$DQG 6&X/+PRGHOV%XOJDULD 7KH&8$ODVHUIURP 2[IRUG /DVHUV ZRUNV ZLWK QHRQ SXPSLQJ7KH RSHUDWLQJ WLPH RI LWV $( RQ D VLQJOH FKDUJH RI FRSSHU LV DERXW  K /DVHUV 6&X/+ DQG 6&X/+ RI WKH ILUP 0DVKLQRH[SRUW DUH PDQXIDFWXUHG ERWK LQ the pumping system and in the sealed-off version. For sealed-off $(V RI IRUHLJQ ODVHUV ZLWK D SRZHU RI ± : WKH PDLQ UHOLDELOLW\ SDUDPHWHU LV WKH VHUYLFH OLIH ± K  ZKLFK LV ± WLPHV OHVV than the guaranteed operating time of the industrial sealed-off Kulon and Kristall. The most powerful Russian industrial sealed-off AE is WKH */& /76L .ULVWDOO  SURGXFHG E\ WKH Istok Company. 7RGD\H[SHULPHQWDOVDPSOHVLQDVHDOHGRIIGHVLJQZLWKDQRXWSXWRI

New Generation of Efficient Sealed-off Active Elements

159

Number

100 90 80 70 60 50

40 30

20 10 0 0 0 0

C'l

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C'l

 ±    ±@ $QRWKHU developing promising direction with the use of CVL is precision micromachining of materials, first of all thin-sheet metal and nonPHWDOOLF PDWHULDOV ± PP  IRU HOHFWURQLF SURGXFWV >  ±±±±   @ 7KH VSHFWUXP RI SURFHVVHG PDWHULDOV LV SUDFWLFDOO\ XQOLPLWHGWKH\DUHUHIUDFWRU\PDWHULDOV:0R7D PHWDOVZLWKKLJK thermal conductivity (Cu, Ag, Al, Au), their alloys, semiconductors 6L*H*D$V6L& GLHOHFWULFVJUDSKLWHVGLDPRQGVDQGRWKHUV7KH so-called optical systems with intensified image brightness occupy a notable place in the field of application of CVL, in which active PHGLD RI ERWK &9/ DQG *9/ DUH XVHG 7KH&9/VDQG*9/VRQWKHEDVLVRIVHDOHGRII$(RIWKH.XORQ series separately and in combination with tunable wavelengths DSLs are widely used in medicine. Especially important is their use for the WUHDWPHQWRIFDQFHUE\SKRWRG\QDPLFWKHUDS\>±   @ $QRWKHU TXLWH VXFFHVVIXO DSSOLFDWLRQ RI WKHP FDQ

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be considered treatment of vascular, pigmented and unpainted skin defects, for smoothing wrinkles, i.e. in dermatology and cosmetology >±@3XOVHGUDGLDWLRQRI&9/ZLWKZDYHOHQJWKVȜ DQG QPDQGDSXOVHGXUDWLRQRI±QVVHOHFWLYHO\FRDJXODWHVVNLQ defects without damaging the surrounding tissue and without causing pain (without anesthesia). The CVLs in combination with DSLs, which allow to obtain effective and powerful tunable generation in the visible and near infrared regions of the spectrum, are also widely used for spectroscopic studies. The radiation of CVLs on the basis of sealedoff AEs of the Kristall series is efficiently transformed by means of non-linear crystals into the second harmonic, that is, into the ultraviolet region of the spectrum with an average output power of ±:7KHODVHUUDGLDWLRQLVDOVRXVHGWRSXPSDWLWDQLXP±VDSSKLUH (Al 22 3 Â 7L +3) laser in order to obtain tunable lasing in the near-IR region, and when doubling the frequency, in the blue region of the VSHFWUXP >      ±@ 6XFK PXOWLIUHTXHQF\ tunable laser systems with a large average generation power are unique. In addition to technological applications, the CVLs and devices based on them have been used for many years for highspeed photography and holography, gas flow visualization, laser acceleration of microparticles, spectroscopic and mass spectroscopic studies, astronomical studies, and projection microscopy, cinema and television, navigation and location (see Chapter 1). The course of the development of research in these areas is widely discussed at numerous all-Russian and international conferences and seminars, which contributes to a stable interest in the CVL from scientific and production organizations.

3.6. Conclusions and results for chapter 3 1. Highly efficient and durable industrial sealed-off self-heating AEs RI WKH SXOVHG &9/ RI D QHZ JHQHUDWLRQ RSHUDWLQJ LQ D PL[WXUH RI copper, neon and hydrogen vapour, the Kulon series of small power ±: DQGWKH.ULVWDOORIPHGLXPSRZHU±: KDYHEHHQ developed.  +LJK PD[LPXP  HIILFLHQF\ SRZHU GXUDELOLW\ TXDOLW\ DQG stability of output radiation parameters in the developed industrial VHDOHGRIIVHOIKHDWLQJ$(VRIWKHSXOVHG&9/ZLWKDSRZHURI±

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:DUHDFKLHYHGGXHWRWKHLPSOHPHQWDWLRQRIDFRPSOH[RIVFLHQWLILF technical and technological solutions: ± SURGXFLQJ D VHFWLRQHG FHUDPLF GLVFKDUJH FKDQQHO ZLWK EOLQG grooves, in each of which a copper vapour generator is installed in the form of a molybdenum substrate with holes wetted by the DFWLYHVXEVWDQFH±PROWHQFRSSHUDQGSHUIRUDWHGHQGWXEHVFHUDPLFV $±$O 22 3   0J2  ± GHYHORSHG WHFKQRORJ\ IRU GHJDVVLQJ $( DQG UHVWRULQJ VXUIDFH purity of copper vapour generators, electrode assemblies and other elements in a hydrogen atmosphere with neon at Twork ƒ&DIWHU complete degassing of AE at T  ƒ& IRU ± K GHSHQGLQJ on the AE model); ± FUHDWLRQ RI DQ XQKHDWHG DXWR WKHUPRHPLVVLRQ PHWDOSRURXV WXQJVWHQ±EDULXP:±%D FDWKRGHRIDULQJVWUXFWXUHZLWKDQDQQXODU groove on the inner surface providing stable local combustion of a SXOVHG DUF GLVFKDUJH DFWLYH VXEVWDQFH ± EDULXP DOXPLQRVLOLFDWH RI FRPSRVLWLRQ %D2 Â$O 22 3 Â &D2 Â 6L2 2); ± D WKUHHOD\HU KLJKWHPSHUDWXUH KHDW LQVXODWRU ZLWK ORZ WKHUPDO FRQGXFWLYLW\ Ȝ  ± :P Â .  DQG D ORZ VSHFLILF JUDYLW\ (ȡ ±JFP 2) based on Al 22 3DQG6L2 2R[LGHVORFDWHGLQWKH space between the discharge channel with T work !ƒ&HOHFWURGH nodes and the outer vacuum-tight shell with T work ! ƒ& ± DSSOLFDWLRQ RI RXWSXW DQWLUHIOHFWLQJ ZLQGRZV ZLWK DQ DQJOH RI LQFOLQDWLRQ WR WKH RSWLFDO D[LV RI WKH$( QRW H[FHHGLQJ WKH YDOXHV D

arctg

(2  ab) , ( 2a  b)

where a  D chan/l chan (D chan is the diameter and l chan is the length of the discharge channel), b  D chan/l w (l w is the distance from the end RI WKH GLVFKDUJH FKDQQHO WR WKH ZLQGRZ DORQJ WKH RSWLFDO D[LV 3. The service life of industrial sealed-off self-heating AEs of the new generation of the Kulon and Kristall series of the pulsed CVL, due to the high reliability of all functional units and effective protection against dusting of the output windows, is determined by only three factors: the mass of stored copper in copper vapour generators, the operating temperature of the discharge channel and WKHSUHVVXUHRIWKHEXIIHUJDVQHRQDQGLVQRWOHVVWKDQKRXUV The reason for the reduction in power during the period after the JXDUDQWHHG RSHUDWLQJ WLPH  KRXUV  LV WKH IRUPDWLRQ LQ PROWHQ copper of molybdenum structures (clusters) with a developed surface,

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increasing the enthalpy (necessary energy) of evaporation of copper from the system.  ([SHULPHQWDO VWXGLHV RQ LQFUHDVLQJ WKH UDGLDWLRQ SRZHU DQG the efficiency of pulsed CVLs in dependence on the conditions of H[FLWDWLRQRI$0ZLWKWKHLQGXVWULDOVHDOHGRII$(VRIWKH.XORQDQG Kristall series were carried out at a pulse repetition frequency in the UDQJH RI ± N+] WKH SUHVVXUHV RI WKH QHRQ EXIIHU JDV RI ± PP +J DQG WKH SDUWLDO SUHVVXUH RI K\GURJHQ XS WR  PP +J 5. The power source with a high-voltage pulse modulator of pumping, produced according to the scheme of capacitive voltage doubling with links of magnetic compression of nanosecond current pulses and an anode reactor, remains the most reliable and efficient pulsed CVL pumping generator. 6. The addition of hydrogen to the active medium of the CVL with D SDUWLDO SUHVVXUH RI ± PP +J OHDGV WR DQ LQFUHDVH LQ UDGLDWLRQ power up to 2 times and an efficiency of 1.5 times, depending on the parameters of the pump current pulse, pulse repetition frequency, neon pressure and the diameter of the discharge channel. The hydrogen is introduced into the AE after a complete cycle of degassing and purification of the AE and at optimal operating WHPSHUDWXUHV aƒ&  7. As the diameter and length of the discharge channel of the AE and, correspondingly, the volume of the active medium increase, the relative decrease in the radiation power with increasing pressure of the neon buffer gas becomes sharper because of the deterioration LQ WKH FKDUDFWHULVWLFV RI WKH SXPS FXUUHQW SXOVHV :KHQ WKH QHRQ SUHVVXUH YDULHV IURP  WR  PP +J DQG WKH  N+] SXOVH repetition frequency, the average radiation power of the CVL with WKH .XORQ $( PRGHO */( ZLWK D GLDPHWHU DQG OHQJWK RI WKH GLVFKDUJH FKDQQHO RI  DQG  PP GHFUHDVHV IURP  WR  : a  WKH .ULVWDOO$( PRGHOV */$ ZLWK D GLDPHWHU DQG WKH OHQJWK RI WKH FKDQQHO  DQG  PP ± IURP  WR  : a  */% ZLWK D GLDPHWHU DQG OHQJWK RI WKH FKDQQHO  DQG  PP ± IURP  WR  : a  */' ZLWK D GLDPHWHU DQG WKH OHQJWK RI WKH FKDQQHO  DQG  PP ± IURP  WR : a  */'ZLWKDGLDPHWHUDQGFKDQQHOOHQJWKRIDQGPPLQ JROG YDSRXUV  ± IURP  WR : E\ a  ,QWKHSXOVHUHSHWLWLRQIUHTXHQF\UDQJHRI±N+]WKHDYHUDJH UDGLDWLRQSRZHURIWKH.ULVWDOO$(VRIWKH*/$*/%DQG */&PRGHOVDWRSHUDWLQJQHRQSUHVVXUHVDQGRSWLPL]HGSXPSLQJ SDUDPHWHUV YDULHV ZLWKLQ 

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8. The efficiency of pulsed CVLs with the industrial sealed-off AE RIWKH.XORQVHULHVZLWKDUDGLDWLRQSRZHURI±:ZLWKGLDPHWHUV of the discharge channel D chan    DQG  PP DQG WKH YROXPH of AM (V AM) from 4 to 85 cm 3 LV ± WKH .ULVWDOO VHULHV ZLWK D SRZHU RI ± : ZLWK D chan   DQG  PP DQG V AM  ± cm 3 ± ± DQG ZLWK D SRZHU OHYHO RI ± : ZLWK D chan  32 and 45 mm and V AM   ± FP 3 ± ±  0RUH LPSRUWDQW SDUDPHWHUV RI WKH $(V RI WKH .ULVWDOO VHULHV are those when operating them in the power amplifier mode, since WKH\DUHPDLQO\XVHGLQKLJKSRZHU&9/VRIWKH02±3$W\SHDVWKH 3$ ,Q WKH &9/6 ZKHQ XVLQJ LQ WKH 02 RI WKH$( LQ WKH */ model, the average power of the radiation and the efficiency of the &9/6 DQG WKH HIILFLHQF\ RI WKH$( */$ DV WKH 3$ ZDV  : DQGUHVSHFWLYHO\ZLWK*/%DVWKH3$±: DQG  ZLWK WKH */& DV WKH 3$ ±  :  DQG  ZLWK /7&X( DV WKH 3$ ±  :   DQG  ZLWK /7&X DV WKH 3$ ±  :  DQG  ZLWK /7& DV WKH 3$ ±  :DQGZKLFKLQ±WLPHVPRUHLQFRPSDULVRQZLWK the generator mode.  ,W LV HVWDEOLVKHG WKDW LQ WKH LQGXVWULDO VHDOHGRII VHOIKHDWLQJ AEs of the Kulon and Kristall series with an increase in the diameter of the discharge channel from D chan   PP ZLWK WKH YROXPH RI WKH active medium V AM ~ 4.2 cm 3 */Ⱥ  WR D chan   PP ZLWK V Ⱥ0 a  FP 3 */&  WKH UDGLDWLRQ SRZHU RI WKH &9/ ZKHQ RSHUDWLQJ LQ WKH JHQHUDWRU PRGH LQFUHDVHV IURP  WR  : LQ WKH 3$ PRGH IURP  WR  : $W WKH VDPH WLPH WKH YROXPH RI $0 LQFUHDVHGDSSUR[LPDWHO\WLPHV DQGWKHUDGLDWLRQSRZHU ± RQO\  WLPHV   7KLV PHDQV WKDW WKH UHODWLYH LQFUHDVH LQ WKHUDGLDWLRQSRZHULVDSSUR[LPDWHO\WLPHVORZHUWKDQWKHUHODWLYH increase in the volume of the AM, which in turn indicates a potential SRVVLELOLW\ RI DFKLHYLQJ SRZHU WDNHRII IURP RQH $( RI WKH */ &W\SH WR :  î   :  11. It was found that at optimal operating temperatures of the GLVFKDUJHFKDQQHORIWKH$(LQWKHUDQJH±ƒ&WKHVSHFLILF power release and the concentration of copper vapour in the AM are related to each other by a direct proportional dependence determined E\ WKH H[SUHVVLRQ ȡ  ȡ   N/N , where ȡ  is the specific power at a vapour concentration of N . How many times the concentration of copper vapour decreases, the power take-off per unit volume of AM decreases as much as again, and vice versa. If the optimum working WHPSHUDWXUHRIWKHFKDQQHORIWKH$(RI*/$D chan PP LV

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DERXW ƒ& WKHQ IRU WKH$( RI WKH */& D chan   PP  LV ORZHU E\ DERXW ƒ& ± ƒ& ZKLFK FRUUHVSRQGV WR D GHFUHDVH LQWKHFRQFHQWUDWLRQRIFRSSHUDWRPVLQWKH$0IURPÂ 15 cm í WR  Â  15 cm í, that is 4 times. The specific power take-off has GHFUHDVHG E\ WKH VDPH IDFWRU ± IURP :FP 3 WR :FP 3. 12. An important conclusion follows from the analysis of the H[SHULPHQWDODQGWKHRUHWLFDOVWXGLHVFDUULHGRXWLQWKLVSDSHULQRUGHU to achieve high efficiency of CVL with large volumes of AM, the AE GHVLJQDQGWKHH[FLWDWLRQFRQGLWLRQVVKRXOGEHVXFKDVWRHQVXUHWKH operating temperature of the discharge channel with copper vapour JHQHUDWRUVDWWKHOHYHOƒ&ZLWKRXWVXSHUKHDWLQJRIWKH$0LH optimal conditions were created for inversion of the populations in the AM at a copper vapour concentration N Cu !  16 cm í. 13. The industrial sealed-off self-heating AEs of the Kulon VHULHV ZLWK D UDGLDWLRQ SRZHU RI ± : DQG RI WKH .ULVWDOO VHULHV ZLWK D SRZHU RI ± : DUH SUHIHUUHG DV UHJDUGV WKH HIILFLHQF\ guaranteed running time and operating conditions in comparison with the similar foreign analogues. The removal of the radiation power from a unit volume of the active medium of the AE of the .XORQ VHULHV LV DSSUR[LPDWHO\  WLPHV KLJKHU LQ WKH .ULVWDOO$(V LW LVWLPHVWKHPLQLPXPRSHUDWLQJWLPHLV±WLPHVODUJHUDQGWKH sealed-off design of the AE does not require additional operational support elements. 14. The total volume of sales of the new generation of industrial sealed-off AEs of the Kulon and Kristall pulsed CVLs for the period IURPWRIRU\HDUV DPRXQWHGWRDERXWXQLWVWKDW LV DQ DYHUDJH RI DERXW  XQLWV\HDU ,Q WKH IROORZLQJ \HDUV LW LV H[SHFWHG WKDW WKH VDOHV ZLOO LQFUHDVH

4

Highly selective optical systems for the formation of single-beam radiation of diffraction quality with stable parameters in copper vapour lasers and copper vapour laser systems Modern fields of application of pulsed copper vapour lasers (CVL) and the more powerful copper vapour laser systems (CVLS) based on them require not only an accurate knowledge of the radiation characteristics, but also the possibility of forming radiation beams ZLWK KLJK QHFHVVDU\  TXDOLW\ DQG FRQWUROOHG SDUDPHWHUV >± @ 7KHVH DUHDV LQFOXGH DGYDQFHG WHFKQRORJLHV IRU SUHFLVLRQ microprocessing of materials for electronic components, separation of isotopes and the production of pure substances for the needs of nuclear power engineering, medical technologies, pumping wavelength-tunable lasers based on dye solutions (DSL) and nonlinear crystals (NC), analysis of the composition of substances, ORFDWLRQ QDQRWHFKQRORJ\ HWF >±@ The present chapter is devoted to the study and development of optical systems for the formation of high-quality single-beam radiation in CVL and CVLS: diffraction divergence and with stable SDUDPHWHUV7RDFKLHYHWKLVJRDOH[SHULPHQWDODQGWKHRUHWLFDOVWXGLHV of the dynamics of the formation of the structure, spatial, temporal, and energy characteristics of the pulsed radiation of CVL and CVLS

Highly Selective Optical Systems

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with optical systems possessing high spatial selectivity were carried RXW ZLWK RQH FRQYH[ PLUURU ZLWK DQ XQVWDEOH UHVRQDWRU 85  ZLWK WZR FRQYH[ PLUURUV DQG D WHOHVFRSLF 85 DQG E\ WKH GHILQLWLRQ of the conditions for the formation in a resonator of single-beam radiation with diffraction divergence and stable parameters. The laser radiation of this quality is focused with the help of short-focus OHQVHV ± PP  LQWR D VSRW ZLWK FOHDU ERXQGDULHV ± ȝP LQ GLDPHWHU DQG D SHDN SRZHU GHQVLW\ RI  ± 12 :FP 2, sufficient for efficient microprocessing of metallic materials and a large range RI VHPLFRQGXFWRUV DQG GLHOHFWULFV >    @ 6LQFH WKH processing is carried out in the evaporation mode in a small section ± ȝP  DQG ZLWK VPDOO YDOXHV RI SXOVHG HQHUJ\ ± P-  DQG KLJKUHSHWLWLRQUDWHV±N+] DKLJKTXDOLW\RIWKHFXWLVDFKLHYHG the heat-affected zone of @ DQG WKHQLQ>±@ZKHUHLWZDVVKRZQWKDWDWODUJHPDJQLILFDWLRQVRI the resonator (M  ±  D EHDP ZLWK D GLIIUDFWLRQ GLYHUJHQFH is formed toward the end of the pulse. But the authors of these works did not fully disclose the dynamics of the formation and structure of the output radiation beam, which turned out to be the most important for practical applications. Somewhat later, in my works and together with other authors we presented the results of ODUJHVFDOH H[SHULPHQWDO DQG WKHRUHWLFDO VWXGLHV RI WKH VWUXFWXUH and characteristics of the radiation of CVL with different types of resonators and the application of the first, most powerful for that time, industrial sealed-off active elements (AE) of the Kristall series WKH */ PRGHO ± :  DQG WKH */( PRGHO ± :  >±@$QGLWZDVHVWDEOLVKHGWKDWWKHRXWSXWUDGLDWLRQRI CVL with the telescopic UR has a multibeam and discrete structure, in which each beam, in the process of formation, competing with each other in power, acquires its spatial, temporal and energy characteristics. The diffraction beam is always preceded by several EHDPV ZLWK JUHDWHU GLYHUJHQFH DQG WKH LQVWDELOLWLHV RI WKH D[LV RI the beam pattern of the diffraction beam are commensurate with its divergence. In this form, the output radiation was simply unsuitable for high-quality microprocessing of materials and that prevented the creation of technological equipment on the basis of CVL. In the same papers, in order to get rid of the multibeam radiation structure, the optical variant alternative to the resonator was first SURSRVHGDQGLQYHVWLJDWHG±WKHRSHUDWLQJPRGHRI&9/ZLWKDVLQJOH FRQYH[PLUURUVLQJOHPLUURUUHJLPH DWVPDOOUDGLLRIFXUYDWXUH>@ ,Q WKH H[SHULPHQWV ZH XVHG WKH VDPH $( .ULVWDOO PRGHOV */ DQG */( ,Q WKLV PRGH WKH VWUXFWXUH RI WKH RXWSXW UDGLDWLRQ is two-beam: an incoherent beam of superradiance formed by the geometric aperture of the active element (AE), and a beam with high spatial coherence formed by the mirror and the output aperture of the AE. The divergence of the second useful beam can be varied ZLWKLQZLGHOLPLWVE\FKDQJLQJWKHUDGLXVRIFXUYDWXUHRIWKHFRQYH[ mirror. Since this beam is formed with the participation of a single PLUURU LW DOVR SRVVHVVHV D KLJK VWDELOLW\ RI WKH D[LV RI WKH UDGLDWLRQ SDWWHUQ$WUDGLLRIWKHFRQYH[PLUURURQHRUWZRRUGHUVRIPDJQLWXGH smaller than the distance from the mirror to the output aperture of the AE, the divergence of the beam becomes close to diffraction. At R íFPWKHGLYHUJHQFHRIWKH&9/EHDPZDVș íPUDG ± WLPHV WKH GLIIUDFWLRQ OLPLW  ZKLFK ZDV VXIILFLHQW WR DFKLHYH D

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GHQVLW\ RI SHDN SRZHU RI  ±  :FP 2 in a focused spot with a diameter d ±ȝPDQGDFFRUGLQJO\IRUWKHSURFHVVLQJRIWKLQ sheet materials. 7KH UDGLDWLRQ FKDUDFWHULVWLFV RI &9/ ZLWK 85 ZLWK WZR FRQYH[ mirrors have not been investigated before and have been investigated only in the framework of this paper, where its capabilities for the technology of microprocessing of electronic component materials have been determined. To date, a series of small-sized modern, high-reliability and effective CVL facilities has been created on the basis of a new generation of industrial sealed-off Kulon AEs with an average UDGLDWLRQSRZHURIWR:VHH&KDSWHU >±@7KH\ are already used for pumping lasers tunable over wavelengths on dye solutions, analysis of the composition of substances, nanotechnology, medicine, etc. But the question of the possibility of their use for microprocessing of materials remained open. Therefore, it made sense to conduct research of optical systems with high spatial selectivity with a new generation of industrial CVLs.

4.2. Experimental settings and research methods 7 K H  H [ S H U L P H Q W D O  I D F L O L W L H V  I R U  V W X G \ L Q J  W K H  V W U X F W X U H  DQ G characteristics of the output beam of pulsed CVL radiation are presented in Figs. 4.1 a and b. The CVL studies were carried out with optical systems possessing high spatial selectivity: in the regime ZLWK RQH FRQYH[ PLUURU WKH VLQJOHPLUURU PRGH )LJ  a), with 85 ZLWK WZR FRQYH[ PLUURUV DQG WHOHVFRSLF 85 )LJ  b). The most powerful industrial sealed-off AE from the Kulon series was XVHGDVDVRXUFHRIJHQHUDWLRQLQWKH&9/WKH*/(PRGHOZLWK WKH SRZHU RI  : DQG WKH */, PRGHO ZLWK D SRZHU RI  : (see Chapter 1). )LJXUH  VKRZV WKHLU DSSHDUDQFH 3XPSLQJ ZDUPLQJ XS DQG H[FLWDWLRQ  RI WKH $( RI WKH &9/ ZDV SURGXFHG E\ D KLJKYROWDJH pulsed power source with a thyratron modulator, produced according to the capacitive voltage doubling scheme with two links of magnetic compression of nanosecond current pulses and an anode reactor )LJ >±@7KHSRZHUVRXUFHZLWKWKLVHOHFWULFDO circuit of the modulator remains the most reliable and efficient pump generator.

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a

b Fig. 4.1.([SHULPHQWDOIDFLOLWLHVIRUVWXG\LQJWKHVWUXFWXUHDQGFKDUDFWHULVWLFVRIWKH output radiation of pulsed CVL with optical systems with high spatial selectivity (a and b 2&±RSWLFDOKRQH\FRPEWDEOHW\SH17ZLWKSQHXPDWLFLQVXODWRUV $3DQG$3ORFDWHGEHWZHHQWKHWDEOHDQGIRXULWVVXSSRUWVPRGHO76  ILUP 6WDQGD  1 ±$( 2 ±$( GLVFKDUJH FKDQQHO A ± FROOLPDWLQJ OHQV ZLWK focal length F PS 1(a LVDFRQYH[PLUURUS 1(b ±S 2(b ±85ZLWKWZRFRQYH[ mirrors; S'1(b)–S'2(b  ± WKH WHOHVFRSLF 85 3 ± IODW URWDU\ PLUURUV D 1 ± GLDSKUDJP with aperture d PPD 2±WKHGLDSKUDJPRIWKHVSDWLDOILOWHUFROOLPDWRU6)&  4 and 5 ± LQSXW DQG RXWSXW FRQFDYH PLUURUV RI D FROOLPDWRU 6)& ZLWK D UDGLXV RI curvature R   P 6 ± EHDP VSOLWWHU SODWH ZLWK UHIOHFWLRQ FRHIILFLHQW ȡ   7 ± IRFXVLQJ PLUURU ZLWK D UDGLXV RI FXUYDWXUH R   P 8 ± QHXWUDO ILOWHU 9 ± D radiation power meter (millivoltmeter M136 with a converter of laser radiation power TI-3); 10±GLJLWDORVFLOORVFRSH*'66ZLWKDSKRWRFHOO)(..11±%HDP6WDU FX beam analyzer; 12 ± ZDWHUFRROHG KHDW VLQN 13 ± IOXRURSODVWLF VHDOLQJ  WXEHV

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Fig. 4.2. 7KHDSSHDUDQFHRILQGXVWULDOVHDOHGRII$(.XORQPRGHOV*/(:  DQG */, : 

Fig. 4.3. The basic electrical scheme of the high-voltage pulse modulator of the power source: 1±KLJKYROWDJHUHFWLILHUFKDUJHU2±WK\UDWURQVZLWFKɌ*, RUɌ*,3±DQRGHUHDFWRU4, 7 and 8±ILUVWVHFRQGDQGWKLUGQRQOLQHDU inductances; 5 and 6±VHULHVFRQQHFWHGVWRUDJHFDSDFLWRUVRIFDSDFLWDQFH  pF; 9±VWRUDJHFDSDFLWRUZLWKDFDSDFLWDQFHRIS)10±DVKDUSHQLQJFDSDFLWRU ZLWK D FDSDFLW\ RI  S) 11 ± $( ZLWK SDUDOOHO LQGXFWDQFH  13 ± FRPPRQ ground bus. Table 4.1.7KHJHRPHWULFGLPHQVLRQVRIWKH$(RIWKHPRGHOVRIWKH*/(DQG */, *HRPHWULFGLPHQVLRQV

lAE, mm

lchan, mm

lAM, mm

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565

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l'1, mm

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172

l AM l chan l AE Fig. 4.4. Schematic representation of AE Kulon CVL without mirrors: 1±YDFXXP tight shell; 2 ± GLVFKDUJH FKDQQHO 3 ± FRSSHU YDSRXU JHQHUDWRUV 4 ± FRQGHQVHUV of copper vapour; 5 ± KHDW LQVXODWRU 6 ± HOHFWURGHV 7 ± RXWSXW ZLQGRZV l AE is the length of the AE; D chan and l chan are the diameter and length of the discharge channel; l AM is the length of the active medium; l  and lc are the distances from the output window to the discharge channel and the active medium, respectively; Į 1 is the angle of propagation of the beam of superradiance.

Figure 4.4 is a schematic representation of the AE Kulon without mirrors. The main functional nodes, overall dimensions of the AE and its discharge channel, necessary for analysis and calculation of the space-time radiation characteristics are shown: l±GLVWDQFHIURP the output window (position 7) to the end of the discharge channel (item 2); l' ± WKH GLVWDQFH IURP WKH RXWSXW ZLQGRZ LWHP   WR WKH active medium of the discharge channel (item 2); lchan is the length of the discharge channel (the distance between the electrodes (item 6)); l AM±OHQJWKRIWKHDFWLYHPHGLXPGLVWDQFHEHWZHHQWKHFRQGHQVHUV of copper vapour (item 4)). AB is the output aperture of the AE, equal to the internal diameter D chan of the discharge channel, Į 1 is the propagation angle of the beam of superradiance formed by the total geometric aperture of the discharge channel (D chan/l chan) from WKH DPSOLI\LQJ HPLVVLRQ :LWKLQ WKLV DQJOH DSSUR[LPDWHO\  RI the energy of the output radiation is concentrated. 7KH JHRPHWULF GLPHQVLRQV RI WKH $( RI WKH PRGHOV */( DQG*/,ZKLFKDUHQHFHVVDU\IRUFDOFXODWLQJWKHGLYHUJHQFHRI radiation, are given in Table 4.1. Table 4.1 also gives the distances that determine the location of WKH FRQYH[ PLUURU S 1 with respect to the AE and its elements; l 1, l'1

Highly Selective Optical Systems

173

and l are the distances from the mirror S 1 to the AE, its AM, and the output aperture. $GXOOFRQYH[PLUURUS1 in the optical circuits a) and b) is installed in a blackened metal frame with a conical surface absorbing the radiation. The output mirror S 2 (b) of the UR is an antireflecting SRVLWLYH OHQV LQ WKH IRUP RI D FRQYH[FRQFDYH PHQLVFXV RQ WKH FRQYH[ VXUIDFH RI ZKLFK D PLUURU VSRW ZLWK D GLDPHWHU RI ± PP LV DSSOLHG SDWHQW 1R    5)  >@ 7KH IRFXV RI WKH mirror lens S 2(b) is aligned with the focus of the blind mirror S 1(b), so that the diverging beam formed by UR is converted (collimated) into a parallel (cylindrical) beam with minimum divergence and that LV FRQYHQLHQW IRU SUDFWLFDO DSSOLFDWLRQV ,Q WKH ILUVW H[SHULPHQWV DQ RXWSXW FRQYH[ PLUURU ZLWK D GLDPHWHU RI  PP ZDV JOXHG to a plane-parallel, antireflecting glass plate (S'2 (b)). The angle EHWZHHQWKHRSWLFDOD[LVRIWKLVPLUURUDQGWKHSODWHZDVƒZKLFK eliminated the inverse ‘parasitic’ connection from the plate with the active medium of the AE. In this case, the beam from the resonator comes out divergent and an additional optical element is required to collimate it into a parallel beam. In the telescopic UR, the focus of a deaf concave mirror S'1(b) is aligned with the focus of the output FRQYH[ PLUURU S'2(b) which is the basic condition for the formation of a parallel beam with a plane wave directly in the resonator. For the convenience of conducting research on the characteristics of a divergent qualitative beam of radiation produced in a CVL in a single-mirror mode (a), it was first collimated into a cylindrical beam using a lens with a focal length F   P L), and then focusing with a spherical concave mirror with R   P LWHP   :KHQUHFRUGLQJWKHRVFLOORJUDPVRISXOVHVDQGUHPRYLQJWKHLQWHQVLW\ distribution in the constriction of the focused radiation beam, the SRZHUZDVSUHYLRXVO\DWWHQXDWHGE\LQWURGXFLQJLQWRWKHOLJKWIOX[D beam splitter plate (position 6) and neutral light filters (position 8). ,Q H[SHULPHQWDO LQVWDOODWLRQV WKH DYHUDJH SRZHU RI WKH UDGLDWLRQ was measured with a millivoltmeter M136 with a TI-3 laser radiation SRZHUFRQYHUWHUFRQQHFWHGWRLWLWHP UHFRUGLQJUDGLDWLRQSXOVHV ZLWK DQ RVFLOORVFRSH RI WKH *'66 W\SH ZLWK D SKRWRFHOO )(. . LWHP   DQG VWXG\LQJ WKH GLVWULEXWLRQ RI UDGLDWLRQ LQWHQVLW\ and measurement of the diameter in the focal plane (practically in the waist of 1/e2 RIWKHIRFXVHGEHDP±%HDP6WDU);EHDPDQDO\]HU (item 11). Since it is assumed that the intensity distribution in the IRFDOSODQHFRUUHVSRQGVWRWKHIDUILHOGGLVWULEXWLRQ!D 2ȜZKHUHD is the diameter of the beam, Ȝ is the wavelength of the radiation),

174

Laser Precision Microprocessing of Materials

then for the practical determination of the divergence (ș) a simple method is the focal spot method:

T

d , F

(4.1)

where d  is the diameter of the focused radiation beam in the focal plane (in the neck), F is the focal length of the focusing optical element. In all the cases considered below, the divergence of the laser radiation was reduced to the diameter of the aperture of its discharge channel (D chan   PP  An important technological parameter in microprocessing by pulsed laser radiation is the density of peak power in a focused spot that determines the quality and productivity of processing. The peak power density is determined by the formula

U

Prad , f ·WS ·r 2

(4.2)

where P rad is the average radiation power, f is pulse repetition IUHTXHQF\ 35)  IJ is the half-height pulse duration, r is the radius RIWKHVSRWRIWKHIRFXVHGEHDPRIUDGLDWLRQ,QRXUH[SHULPHQWVWKH ZRUNLQJ 35) RI WKH &9/ ZDV f  ± N+] WKH SXOVH GXUDWLRQ DW half-height was IJ  ± QV

4.3. Structure and characteristics of radiation of CVL in single-mirror mode. Conditions for the formation of singlebeam radiation with high quality ([SHULPHQWDO VWXGLHV RI WKH FKDUDFWHULVWLFV RI SXOVHG &9/ UDGLDWLRQ in a single-mirror regime, as mentioned above, were carried out in WKH UHJLPH ZLWK D VLQJOH FRQYH[ PLUURU LQ WKH VHWXS VKRZQ LQ )LJ 4.1 a. Figure 4.5 shows separately the optical scheme for this mode. Investigations and calculations were carried out for two cases of WKH DUUDQJHPHQW RI WKH FRQYH[ PLUURU S 1 relative to the AE: at l 1   PP DQG l 1   PP VHH )LJ  DQG7DEOH   In the single-mirror mode, in accordance with the results of RXU LQYHVWLJDWLRQV LQ >  @ DQG LQ WKH SUHVHQW ZRUN WKH output radiation of the CVL has a strictly two-beam structure: an incoherent beam of superradiance I (Fig. 4.5), formed from amplified

Highly Selective Optical Systems

175

AE

D chan

l OE

S1

l AM l chan l AE

OE

Fig. 4.5. The optical scheme of CVL with the Kulon AE in single-mirror mode ZLWK RQH FRQYH[ PLUURU  l AE ± OHQJWK RI$( l chan and D chan ± OHQJWK DQG GLDPHWHU of the discharge channel; l AM is the length of the active medium; S 1±FRQYH[PLUURU with radius of curvature R 1; l 2( is the distance from the mirror S 1 to the collimating RU IRFXVLQJ RSWLFDO HOHPHQW RI WKH 2( A 1B 1 ± LPDJH RI WKH RXWSXW DSHUWXUH RI WKH discharge channel AB in the mirror Z 1; l 1 and l'1± GLVWDQFH IURP PLUURU S 1 to AE and to AM; l is the distance from mirror S 1 to the output aperture AB; f 1±GLVWDQFH from the mirror S 1 to the image A 1B 1; Į 1 ± DQJOH RI SURSDJDWLRQ RI WKH EHDP RI superradiance formed by the total aperture of the discharge channel; Į 2 is the angle of propagation of the beam of superradiance formed by the mirror S 1 and the output DSHUWXUH RI WKH GLVFKDUJH FKDQQHO $% , DQG ,, ± WKH LQWHQVLW\ GLVWULEXWLRQ RI WKH beams of superradiance in the near zone.

spontaneous emission by the total geometric aperture of the AE discharge channel, and a beam II with high spatial coherence formed with the participation of mirror S 1 and the output aperture of the discharge channel AB. Hereinafter, the first incoherent beam will be referred to simply as a background beam, as unsuitable for practical DSSOLFDWLRQVWKHVHFRQGZLWKDKLJKFRKHUHQFH±DTXDOLWDWLYHEHDP Based on the consideration of the geometric path of the rays in WKH &9/ ZLWK D VLQJOH FRQYH[ PLUURU VHH )LJ   WKH GLYHUJHQFH of the collimated qualitative radiation beam, i.e., transformed LQWR D F\OLQGULFDO EHDP ZLWK D PLQLPXP GLYHUJHQFH > @ LV calculated. The condition for collimating this beam is the alignment RIWKHIRFXVRIWKHRSWLFDOHOHPHQW2( ZLWKWKHSODQHRIWKHLPDJH A 1 B 1 of the output aperture AB of the discharge channel in the FRQYH[ PLUURU S 1 (Fig. 4.5). Image A 1B 1 physically represents an imaginary radiation source equivalent to AE with a single mirror. The divergence of the collimated beam is determined by the ratio of the image size A 1B 1 in the mirror to the distance from the image WR WKH 2(

176

Laser Precision Microprocessing of Materials A1 B1 . f L

T

To determine the location (f) and the size (A 1B 1) of the image, we XVH IRUPXODV   DQG   IRU D FRQYH[ VSKHULFDO PLUURU 1 1  l f H h



R , 2

f , l

(4.3) (4.4)

where l is the distance from the object (AB) to the mirror (Fig. 4.5); f is the distance from the image (A 1B 1) of the object in the mirror to the mirror (S 1); h and H are the sizes of the object (AB) and the image (A1B1) of the object in the mirror (S1); AB AƍBƍ Dchan is the GLDPHWHURIWKHDSHUWXUHRIWKHGLVFKDUJHFKDQQHORIWKH$(:KHUHLQ A1B1·L , D Dchan R / 2 A1B1 ( H ) . R/ 2l f

Then the minimal (limiting) divergence of the radiation beam (without allowance for diffraction) is RDchan l

T

L ª º «¬ R  l ( R  2l ) »¼ .

(4.5)

As the value of R tends to zero, the divergence ș also tends to zero. Actually, because of the diffraction on the output aperture, the AE ș tends to the diffraction limit ș diff  ȜD (D  D chanL/l is the GLDPHWHURIWKHUDGLDWLRQEHDPDWWKH2( 7DNLQJWKLVLQWRDFFRXQW WKH H[SUHVVLRQ IRU WKH GLYHUJHQFH LV ZULWWHQ LQ WKH IRUP RDchan l For L  1 we obtain

T lim

T

L ª º «¬ R  l  2 R  2l »¼  T dif .

R·Dchan O  2.44 . 2l ( R  l ) Dchan

(4.6)

(4.7)

Highly Selective Optical Systems

177

The divergence determined by formula (4.7) corresponds to the divergence of the radiation beam, reduced to the diameter D chan of the aperture of the discharge channel AE. If the focal length F of the optical element is less than L, then the radiation beam is focused into a spot with a diameter d

­ 1 1ªL R º½  «  ¾.  F l l R 2l »¼ ¿ ¬ ¯

T®

(4.8)

Then, to determine the radiation power density in a focused spot, we have the following formula: 2

U

­ 1 1ªL R º½ ®  «  ¾  F l l R 2l »¼ ¿ ¬ 4 Prad ·¯ , 2



ST lim

where P rad is the average radiation power of a qualitative radiation beam. $QDO\VLV RI IRUPXODV   DQG   LPSOLHV WKDW WKH GLYHUJHQFH and radiation power density can be varied within wide limits, changing the curvature radius RRIWKHFRQYH[PLUURUDQGWKHGLVWDQFH l from the mirror to the output aperture AB :KHQ R is one or two orders of magnitude smaller than the distance l, the beam divergence ș becomes close to the diffraction limit: ș  ±ș dif. An increase in the distance lLVQRWDOZD\VH[SHGLHQWVLQFHLQWKLVFDVHGXHWRWKH OLPLWHGWLPHRIH[LVWHQFHRISRSXODWLRQLQYHUVLRQWKHUDGLDWLRQSRZHU is substantially reduced. Figure 4.6 shows the dependence of the calculated divergence, )LJ  ± WKH DYHUDJH UDGLDWLRQ SRZHU ZLWK D FKDQJH LQ WKH UDGLXV RIWKHFRQYH[PLUURU S 1ZLWKLQWKHUDQJHRI±FPIRUWKH.XORQ $( RI WKH PRGHOV */( ɚ  DQG */, b  )RU$( */( DQG */, ZLWK D FKDQQHO DSHUWXUH GLDPHWHU D chan   PP WKH diffraction divergence is ș difr   PUDG Curves 1 and 3 in Fig. 4.6 are calculated for the distance from the mirror to the AE l 1   PP 2 and 4 for l 1   PP 7KH larger the distance l 1 and the longer the discharge channel l chan and, correspondingly, the distance from the mirror to the output aperture AB (l) AE, the smaller the divergence of the qualitative beam (curve 4  7KH$( RI WKH .XORQ VHULHV PRGHO */, LV ORQJHU WKDQ WKH $( RI WKH */(  E\  PP

Laser Precision Microprocessing of Materials

178

mrad

mrad 0,5

0 ,5

1 /

v

0,4

v

/

0,3

/

0,2

/

/

/

/

/

0,4

'2

/

3

//

0 ,3

/

0,2

/ v

0,1

/ v /

/

v

/

v ~

/

0,1

0

0

0,5 1,0

2,0

aa

0,5 1,0

3 ,0

R, cm

2,0

3,0

b

R, cm

Fig. 4.6. Dependence of the calculated divergence of the qualitative radiation beam RIWKH&9/ZLWKWKH.XORQ$(RIWKHPRGHOV*/(a DQG*/,b) in the single-mirror regime (a RQWKHUDGLXVRIFXUYDWXUHRIWKHFRQYH[PLUURUS 1. Curves 1 and 3 are calculated for l 1   PP FXUYHV 2 and 4 for l 1   PP

P rad, W

P rad, W

5,0

__ ~.--

4,0 3,0 2,0

1,0

*

v

..

-- ~,....

.- ~---'3

::ll< /

... . . . v

...... ~

7,0 6,0 5,0 4,0 3,0 2,0 1,0

f.-,)-/

*

,

v

>"

,.

......

v

3

~ ~

2

R, cm 2 R, cm 0 a a b Fig. 4.7. The dependence of the average power in the total (1), background (2) and qualitative (3  UDGLDWLRQ EHDPV RI WKH &9/ ZLWK WKH $( .XORQ */( a) and */, b  LQ WKH VLQJOHPLUURU PRGH RQ WKH UDGLXV RI FXUYDWXUH RI WKH FRQYH[ mirror. l 1   PP x ± SRZHU RI WKH EHDP RI VXSHUUDGLDQFH ZLWKRXW PLUURUV 0

1

7KH H[SHULPHQWDO YDOXHV RI WKH GLYHUJHQFH RI WKH TXDOLWDWLYH radiation beam were determined from the results of measurements of the minimum diameter in the constriction of the focused beam )LJXUH  LWHP   DQG XVH RI IRUPXOD   )RU H[DPSOH LQ Fig. 4.8 (color insertion) shows the distribution of the intensity of radiation in the constriction in the operating mode of CVL with AE */, DQG D FRQYH[ PLUURU ZLWK R   FP DW l 1   PP The following notations are indicated on the intensity distribution ILHOG KRUL]RQWDOO\ : : ):+0 &RUUHODWLRQ 3HDN+HLJKW : LV

Highly Selective Optical Systems

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179

Horizontal distribution

Fig. 4.8. Distribution of the intensity of the output radiation beam of the CVL with WKH */,$( LQ WKH VLQJOHPLUURU PRGH LQ WKH IRFDO SODQH ZDLVW  RI WKH PLUURU with the curvature radius R   P R 1   PP l 1   PP

the size of the waist, defined as the half-width of the profile with respect to the 1/e 2 OHYHO IURP WKH PD[LPXP LQWHQVLW\ RI WKH EHDP : LV WKH WRWDO ZLGWK RI WKH SURILOH DORQJ WKH e 2 level from the PD[LPXP LQWHQVLW\ RI WKH EHDP ):+0 LV WKH WRWDO ZLGWK RI WKH SURILOH DW WKH KDOI PD[LPXP EHDP LQWHQVLW\ &RUUHODWLRQ LV WKH EHVW correlation correspondence between the beam profile and the ideal *DXVVLDQ EHDP 3HDN+HLJKW LV WKH KHLJKW RI WKH EHDP SHDN:FP 2. The diameter of the waist at the level 1/e 2  : LQ )LJ   IURP WKH PD[LPXP LQWHQVLW\ ZDV  PP WKH GLYHUJHQFH RI WKH EHDP LQ DFFRUGDQFH ZLWK WKH IRUPXOD   ± ș !  PUDG ZKLFK DJUHHV ZHOO ZLWK WKH FDOFXODWHG YDOXH ± ș   PUDG VHH FXUYH  in Fig. 4.6). It follows from the horizontal intensity distribution that the degree of beam correlation in the single-mirror mode with the *DXVVLDQ EHDP LV  :LWK DQ LQFUHDVH LQ l 1 IURP  WR  PP WKH UDGLDWLRQ SRZHU GHFUHDVHG LQVLJQLILFDQWO\ ± E\  ZKLFK LV LQVLJQLILFDQW LQ WKH contribution to the power density in comparison with the decrease in the divergence. )LJXUH  VKRZV H[DPSOHV RI RVFLOORJUDPV RI WKH EDFNJURXQG incoherent (1) and qualitative (2) radiation beams of CVL with the $( .XORQ */, DW UDGLL RI FXUYDWXUH RI WKH FRQYH[ PLUURU R     DQG  FP DQG WKH GLVWDQFH IURP WKH PLUURU WR WKH$( l 1   PP $W l 1   PP WKH WLPH RI GRXEOH WUDQVPLVVLRQ E\ WKH radiation of the distance from the mirror to the active medium is

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180

R=0,6cM

I

/

I

I ..1..

I

\v/

v

I

~

2

1-- -

.... .... 1'--. .... .......

~

I

r< I

''

j

I

~I

I I

2 /""-. 1

1'----

-

2.5 ns

R=2,0cM

I

I

I I

I

1 ~7 j

R=3 ,0cM

;f---" -@$WWKHVDPHSRZHU OHYHOV WR PD[LPL]H WKH SURGXFWLYLW\ DQG TXDOLW\ RI WKH PDWHULDO microprocessing, it is necessary that single-beam radiation has a diffraction divergence and stable parameters.

Highly Selective Optical Systems

187

4.4. Structure and characteristics of the laser radiation in the regime with an unstable resonator with two convex mirrors Conditions for the formation of single-beam radiation with diffraction divergence and stable parameters In order to obtain single-beam radiation with a diffraction divergence DQG KLJK VWDELOLW\ RI WKH D[LV SRVLWLRQ RI WKH UDGLDWLRQ SDWWHUQ DQG pulsed energy in CVL, studies were made of the spatial, temporal and energy characteristics of the laser radiation in the regime with an XQVWDEOHUHVRQDWRU85 ZLWKWZRFRQYH[PLUURUV7KHH[SHULPHQWDO setup is shown in Fig. 4.1 b and separately Fig. 4.13 shows the optical scheme with the indication of the geometric dimensions necessary for the calculation of the divergence and time parameters of the radiation pulses.

1

OE

D chan

lS

S1 l AM

S2

l chan l AE Fig. 4.13. The optical scheme of the CVL with the AE Kulon in the mode with UR ZLWK WZR FRQYH[ PLUURUV S 1 and S 2 are the ‘dumb’ and output mirrors of the UR with curvature radii R 1 and R 2; D ± GLDSKUDJP ZLWK d   PP L ± OHQJWK RI WKH resonator, l Ⱥ( ± OHQJWK Ⱥ( l chan and D chan ± OHQJWK DQG GLDPHWHU RI WKH GLVFKDUJH channel; l AM±OHQJWKRIWKH$0l 1 and Oƍ1±GLVWDQFHIURPPLUURUWR$(DQGWR$0 l2 and l'2±GLVWDQFHIURPPLUURUWR$(DQGWR$0lS is the distance from the mirror 2 S 2 to the output aperture AB of the discharge channel; Į 1 is the angle of propagation of the incoherent superradiance beam formed by the total geometric aperture of the discharge channel; Į 2 is the propagation angle of the resonant (qualitative) radiation EHDP,DQG,,±WKHGLVWULEXWLRQRIWKHLQWHQVLW\RIWKHVXSHUUDGLDQFHEHDPDQGWKH UHVRQDWRU UDGLDWLRQ EHDP LQ WKH QHDU ]RQH 2( ± FROOLPDWLQJ RU IRFXVLQJ RSWLFDO element or optical system.

188

Laser Precision Microprocessing of Materials

7KH XQVWDEOH UHVRQDWRU 85  ZLWK WZR FRQYH[ PLUURUV LQ comparison with the known telescopic UR and the single-mirror PRGH SRWHQWLDOO\ KDV PD[LPXP VSDWLDO VHOHFWLYLW\ DQG DFFRUGLQJO\ the possibility of forming a single-beam radiation with a minimum (diffraction) divergence. A careful analysis of earlier studies on the dynamics of the formation of a multibeam structure of the output radiation in SXOVHG &9/V ZLWK RSWLFDO UHVRQDWRUV > ± ±@ DQG RXU H[SHULPHQWDO VWXGLHV DQG FDOFXODWLRQV ZLWK 85 DOORZHG XV WR HVWDEOLVK WKDW LQ WKH 85 ZLWK WZR FRQYH[ PLUURUV D VWULFWO\ VLQJOH beam radiation of diffraction quality can form (Į 2 D chan/l) directly on the background of an incoherent aperture superradiance beam (Į 1   D chan /l chan ), but with the obligatory fulfillment of three interrelated conditions: 1. A blind mirror S 1 of the UR must be installed at a distance from the AS equal to at least half the length of the AM and the distance from the output mirror S 2 to the AM and not more than half the distance traveled by the radiation during the lifetime of the inversion and the sum of the length of the AS and the distance from the output mirror S 2 to the AM, that is,

lAM W ·c  l1c  l1c  inv  (lAM  l2c ). 2 2

(4.11)

This is a very important position, since it allows us to begin the process of forming a resonator beam from the output mirror S 2. And then the beam formation in the resonator proceeds in the following VHTXHQFH $0 ĺ RXWSXW PLUURU S 2 ĺ Ⱥ0 ĺ D EOLQG PLUURU S 1 ĺ Ⱥ0 ĺ DQ RXWSXW IURP WKH VLGH S 2). At the initial stage, a part of the radiation from an aperture superradiance beam with Į 1  D chan/ l chan is reflected by the mirror S 2 is reflected back to the AM of the discharge channel. Then, amplified in the AM of the discharge channel, it manages to leave earlier from the end which is near to the blind mirror S 1 before the part of the radiation reflected from the same aperture beam of superradiance reaches the AM. In this case, the reflected part of the radiation from the mirror S 1 from the superradiance beam with Į 1  D chan/l chan does not receive the preferential amplification in the AM and decays. That is, conditions are practically created that prevent the appearance of a second beam, which is ‘parasitic’ for our case, with a divergence close to the diffraction one.

Highly Selective Optical Systems

189

2. The output mirror S2 of the UR should be as close to the AE as possible and have a radius of curvature greater than that of the blind mirror S 1. In order to ensure that the selectivity of the radiation in WKHUHVRQDWRULVPD[LPDOWKHEOLQGPLUURUPXVWKDYHDVPDOOUDGLXV of curvature (R1 ±FP DVLQWKHVLQJOHPLUURUPRGH ±E\± orders of magnitude less than the distance from the mirror S 1 to the output aperture of the discharge channel AB (R 1 < l± 8QGHU these conditions, the feedback from the mirror S2 with the AM begins earlier and from a larger working surface, which is in addition to the first condition that prevents the second unwanted beam from coming from the mirror S 1 with a divergence close to the diffraction one. 3. Under the conditions of sections 1 and 2, the parameters of UR must satisfy the requirements ensuring the formation of a diffraction beam of radiation already for the first double pass of radiation in the resonator, otherwise the practical application of UR with two FRQYH[ PLUURUV LV ORVW To fulfill the third condition, it was necessary to establish the dependence of the divergence of the resonator beam (ș) formed in it for the first double pass of the radiation, on the parameters of the UR, geometric dimensions of the discharge channel (aperture) of the AE and the dimensions connecting them with each other. To this end, it was necessary to derive a formula for the calculation RI GLYHUJHQFH WR SHUIRUP FDOFXODWLRQV DQG H[SHULPHQWDO VWXGLHV IRU small radii of curvature of mirrors. To derive the formula, using the laws of geometric optics, an optical circuit was constructed (Fig. 4.14) for successive displacements of the image of the aperture of WKH$0LQWKHFRQYH[PLUURUVRIWKHUHVRQDWRULQWKHUHFHLYHGEHDP formation direction (see section 1) and indicating the necessary FDUU\LQJ RXW FDOFXODWLRQV RI JHRPHWULF GLPHQVLRQV :KHQ LQ RUGHU to determine the location of the image and its dimensions, we used IRUPXODV   DQG   IRU D FRQYH[ VSKHULFDO PLUURU 1 1 R (4.12)   l f 2 and H f (4.13) , h l where l LV WKH GLVWDQFH IURP WKH REMHFW WR WKH PLUURU LQ )LJ  ± lS and lS2); f±GLVWDQFHIURPWKHLPDJHRIWKHREMHFWLQWKHPLUURUWR 1 WKHPLUURULQ)LJ±f1 and f2); h and H are the size of the object DQG WKH LPDJH RI WKH REMHFW LQ WKH PLUURU LQ )LJ  ± AB, AƍBƍ and A 1B 1, A 2B 2). AB AƍBƍ D chan is the diameter of the aperture of

190

Laser Precision Microprocessing of Materials lS lS

1

2

S2

S1

l chan

Fig. 4.14.2SWLFDOVFKHPHRIVHTXHQWLDOPRYLQJRIWKHLPDJHRIWKHDSHUWXUHRI$( LQFRQYH[PLUURUVRI85AB AƍBƍ±RXWSXWDSHUWXUHVRIWKHGLVFKDUJHFKDQQHORI the AE; l chan is the length of the AE discharge channel; L is the resonator length; S 1 and S 2DUHWKHµEOLQG¶DQGRXWSXWFRQYH[PLUURUVRI85ZLWKWKHUDGLXVRIFXUYDWXUH of R 1 and R 2; l is the distance from the mirror S 1 to the output aperture AƍBƍ l S is 2 the distance from the mirror S 2 to the output aperture AB; A 1B 1 is the image in the mirror S 2 of the output aperture AB; f 2 isd the distance from the mirror S 2 to the image A 1B 1; l S is the distance from the mirror S 1 to the image A 1B 1; A 2B 2 is the 1 image of the image A 1B 1 in the mirror S 1; f 1 is the distance from the mirror S 1 to the image A 2B 2; Aƍ1Bƍ1 is the image of output aperture AƍBƍ LQ LPDJH A 2B 2.

the discharge channel of the AE. The formula obtained for calculating the divergence of the radiation beam (with allowance for the diffraction limit) has the following form:

T

Dchan ·R1·R2 2.44O  , 4·( R1  2 f 2  2 L)( R2  2l32 )(l  f1 ) Dchan

(4.14)

where

f2 f1

R2 ·lS2 R2  2lS2 R1·lS1 R1  2lS1

, lS 2

lAE  l  l2 , 2

R1 ( L  f 2 ) . R1  2( L  f 2 )

Tables 4.2 and 4.3 show the results of calculating the divergence of the output radiation beam using the formula (4.14) for the CVL ZLWK WKH$( .XORQ RI WKH PRGHO */( IRU GLIIHUHQW UDGLXVHV RI curvature of the output mirror S285±R2 DQGFP the radius of curvature of the blind mirror is S 1R 1   FP DQG WKH

Highly Selective Optical Systems

191

7DEOH  */( l 1   FP l 2   FP l S    FP l   FP L   FP 2

R2, cm

1.5

3

5

12

25

șîí, rad











7DEOH  */( l 1   FP l 2   FP l S    FP l   FP L   FP 2

R2, cm

1.5

3

5

12

25

șî , rad











í

Table 4.4 */,  l 1   FP l 2   FP l S    FP l   FP L   FP 2

R2, cm

1.5

3

5

12

25

șî , rad











í

Table 4.5.*/,l 1 ɫPl 2 ɫPl S  ɫPl ɫPL ɫP 2

R2, cm

1.5

3

5

12

25

șî , rad











í

distances from the blind S1DQGWKHH[LWS2 mirrors to AE, respectively, are l1 DQGFPDQGl2 FP)LJ 7KHGLDPHWHURIWKH aperture of the AE D chan   PP ([SHULPHQWDO VWXGLHV ZHUH DOVR carried out at the same radii of mirrors and distances to the AE. The results of calculating the divergence of the radiation from WKH &9/ ZLWK WKH$( */, DUH SUHVHQWHG LQ7DEOHV  DQG  )URPWKHDQDO\VLVRI7DEOHV±LWIROORZVWKDWZLWK85ZLWK WZR FRQYH[ PLUURUV ZKHQ WKH UDGLXV RI FXUYDWXUH RI WKH EOLQG R 1 (3 cm) and the output R 2DQGFP PLUURUVLV±RUGHUVRI magnitude smaller than the resonator length LDQG cm), the divergence of the beam formed for the first double pass of radiation in the resonator becomes equal to the diffraction limit (ș dif   ā  í rad). Thus, the calculations show that the use of KLJKO\VHOHFWLYH85ZLWKWZRFRQYH[PLUURUVLQ&9/LQFRPSDULVRQ with the known types of resonators, makes it possible to form a beam of diffraction quality already for the first double pass of radiation in the resonator and directly from the incoherent aperture beam of superradiance. Tables 4.6 and 4.7 show the measured values of the total average power (P) and power in the diffraction beam of radiation (P difr) of WKH &9/ ZLWK WKH $( .XORQ */( IRU GLIIHUHQW YDOXHV RI WKH

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Table 4.6. The radiation power of the total and the diffraction beam of the CVL ZLWK WKH$( .XORQ */( DW l 1   FP R2, cm



3

5

12

™3:

2.6

1.4

2.3

1.8

3difr:









Table 4.7. The radiation power of the total and the diffraction beam of the CVL ZLWK WKH$( .XORQ */( DW l 1   FP R2, cm



3

5

12

™3:

2.6

1.54

2.4

2.3

3difr:









radius of curvature of the output mirror S 2: R 2     DQG  FP and the constant radius of curvature of the blind mirror S 1: R 1   cm and the distance from the output mirror S 2 to the AE l 2 FP For R 2   ZKHQ WKH PRGH LV VLQJOHPLUURU LH WKHUH LV QR RXWSXW mirror S 2, the qualitative beam is not strictly diffractive, since its GLYHUJHQFHLV±WLPHVWKDWRIWKHGLIIUDFWLRQOLPLW7DEOHVKRZV the power values at a distance from a blind mirror S 1 WR Ⱥ( l 1   FP LQ7DEOH  ± l 1   FP As can be seen from the tables, the value of the average radiation power in the diffraction beam is in the range P difr  ±:7KH power at l 1   FP LV VOLJKWO\ KLJKHU WKDQ DW l 1   FP VLQFH WKH conditions for the non-competitive formation in the resonator of the diffraction beam l 1 FPDUHFORVHUWRWKHIXOILOOPHQWRIWKHEDVLF first condition. )LJXUH  VKRZV H[DPSOHV RI RVFLOORJUDPV RI WKH EDFNJURXQG incoherent 1 and diffraction 2 radiation beams. The total duration of the radiation pulse along the base was IJ # 25 ns. As can be seen from the oscillograms, the beginning of the pulse of the diffraction beam of radiation 2 lags behind the EDFNJURXQG EHDP RI VXSHUUDGLDQFH  E\ DSSUR[LPDWHO\ ± QV which practically corresponds to one double pass of the radiation in WKH UHVRQDWRU ǻt  L/c) and the logic of the process of formation RI WKH GLIIUDFWLRQ EHDP LQ WKH GLUHFWLRQ RI WKH$0 ĺ S 2 ĺ$0 ĺ S 1 ĺ Ⱥ0 ĺ RXWSXW FRQGLWLRQ   ,Q H[SHULPHQWDO VWXGLHV LQ WKH ODERUDWRU\  RI WKH LQWHQVLW\ distribution in the spot of the focused beam of radiation (in the

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@ DQG WKH PHWKRGV DQG PHDQV RI PHDVXUHPHQW DUH VLPLODU WR those presented in the sections 4.2 and 4.3. In this CVLS, as in the V\VWHPV FRQVLGHUHG DERYH WKH$( LQ WKH 02 LV UHSUHVHQWHG E\ WKH VHDOHGRII$( PRGHO */ In order to reduce the inductance of the discharge circuit, the $( */( ZDV SODFHG LQ D FRQLFDO VFUHHQ PDGH RI HLJKW FRSSHU VWULSV PHDVXULQJ  î  FP 7KH VFUHHQ GLDPHWHU DW WKH DQRGH QRGH RI WKH $( ZDV  FP DQG DW WKH FDWKRGH  FP 7KH $( SURYLGHG KHDWLQJ DQG H[FLWDWLRQ IRU D WZRFKDQQHO V\QFKURQL]HG high-voltage power source with water-cooled hydrogen thyratrons in high-voltage modulators of nanosecond pump pulses and with a FRPPRQ WULJJHU SXOVH JHQHUDWRU ,Q WKH PRGXODWRU IHHGLQJ WKH 02 WKH WK\UDWURQ Ɍ*, ZDV XVHG LQ WKH PRGXODWRU VXSSO\LQJ 3$ WKHPRUH SRZHUIXOWK\UDWURQɌ*,ZDVLQVWDOOHV$WWKH RXWSXW RI WKH WULJJHULQJ SXOVH JHQHUDWRU D GHOD\ OLQH “ QV  ZDV FRQQHFWHG WR HQVXUH V\QFKURQL]DWLRQ RI WKH OLJKW SXOVHV RI WKH 02 DQG WKH 3$ 7R LQFUHDVH WKH H[FLWDWLRQ HIILFLHQF\ RI WKH $( WKH high-voltage modulators were made according to the scheme with a transformer voltage doubling and a magnetic link of the current pulse compression. The compression link was a water-cooled copper WXEHZLWK010IHUULWHULQJVWKUHDGHGRQLWZLWKWKHGLPHQVLRQV .îîPP7KHQXPEHURIULQJVLQWKHFRPSUHVVLRQ02ZDV  LQ WKH 3$ ±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± FP DQG ZLWK a telescopic UR with an increase in M   > @ $Q 6)& ZDV LQVWDOOHG EHWZHHQ WKH 02 DQG WKH 3$ LQWHQGHG WR LVRODWH WKH TXDOLWDWLYHEHDPRIWKH02DQGWRPDWFKLWZLWKWKHDSHUWXUHRIWKH GLVFKDUJHFKDQQHORIWKH3$7KHFKDUDFWHULVWLFVRIWKH$(*/(

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with flat and planar (R   P  UHVRQDWRUV ZHUH LQYHVWLJDWHG 7KH UHIOHFWLRQFRHIILFLHQWRIWKHEOLQGPLUURUVLQWKHUHVRQDWRUVZDV A plane-parallel plate without a coating was used as an output mirror. Characteristics of the sealed-off AE GL-201E in the regime of a generator with flat and planar resonators and in the regime with one convex mirror.,QWKH&9/ZLWKWKH$(.ULVWDOO*/(ZKHQ working with a flat resonator, the total average output beam power ZDV  : ZLWK D SODQHVSKHULFDO UHVRQDWRU  : WKH GXUDWLRQ RI WKHUDGLDWLRQSXOVHVDWWKHEDVHZDVQV$ERXWRIWKHSRZHU in both cases was concentrated in the beams formed directly by the UHVRQDWRU DQG  LQ WZR DOZD\V SUHVHQW  VXSHUUDGLDQFH EHDPV >±@7KHJHRPHWULFGLYHUJHQFHVRIWKHVXSHUUDGLDQFHEHDPVDUH DQGPUDG1RPRUHWKDQ±RIWKHSRZHUZDVFRQFHQWUDWHG in a beam with ș geom   PUDG The divergence of the resonator radiation beam when working with a plane resonator was about 3 mrad, which is 3.5 times smaller than when working with a plane-spherical resonator, which value is 45 times larger than the diffraction limit (ș dif PUDG 8VXDOO\ the beams with low divergence are produced using telescopic URs with an increase of M  ±:KHQ WKH$( */( ZLWK 85 was operating, the percentage of power in the diffraction beam was QRPRUHWKDQ±7KHUHIRUHLWLVDGYDQWDJHRXVWRXVHORQJ$(V DV WKH 3$ IRU SRZHUIXO &9/6 In the case of a single-mirror operating mode of the CVL, the output radiation has a strictly two-beam structure: it contains superradiance beams with ș geom   DQG  PUDG 7KH UDGLDWLRQ characteristics of the second beam (șgeom PUDG FDQEHFRQWUROOHG ZLWKLQ ZLGH OLPLWV FKDQJLQJ WKH UDGLXV RI FXUYDWXUH RI WKH FRQYH[ PLUURU > @ :KHQ WKH UDGLXV RI WKH PLUURU LV WZR RUGHUV RI magnitude smaller than the distance from the mirror to the output aperture of the AE, this radiation beam has a quality close to the diffraction one, so that it can be collimated into a narrowly focused cylindrical beam, focused into a spot of small diameter with a high SHDNSRZHUGHQVLW\a11:FP2), as well as isolated by means of a spatial filter from a background (aperture) beam with low coherence  PUDG  )RUWKH$(*/)LJVKRZVWKHGHSHQGHQFHRIWKHDYHUDJH radiation power in the total (curve 1), background (2) and qualitative (3) beams and the calculated divergence of the qualitative beam (4  RQ WKH UDGLXV RI FXUYDWXUH RI WKH FRQYH[ PLUURU 7KH FDOFXODWHG

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P rad, W 15

0,3

10

0,2

5

0,1

0

1

225

2

3

4

R, cm R,cM

Fig. 4.31. Dependences of the average radiation power in the total (1), background (2), qualitative (3) beams and the calculated divergence (4) of the qualitative beam RI &9/ ZLWK WKH$( */( RQ WKH UDGLXV RI FXUYDWXUH RI WKH FRQYH[ PLUURU

GLYHUJHQFH DJUHHV ZHOO ZLWK WKH H[SHULPHQWDO GDWD$ FKDQJH LQ WKH UDGLXVRIFXUYDWXUHRIWKHPLUURUIURPWRFPOHDGVWRDFKDQJH LQ WKH SRZHU LQ D TXDOLWDWLYH EHDP IURP  WR  : FXUYH 3), the FDOFXODWHGGLYHUJHQFHIURPWRPUDG)RUWKH$(*/GXH to its shorter length, the same divergences are achieved with smaller UDGLL RI FXUYDWXUH 7KXV IRU D */( D EHDP ZLWK D GLYHUJHQFH RI  PUDG LV IRUPHG DW R   FP DQG IRU WKH $( */ ± DW R FPEXWLQWKHODWWHUFDVHWKHUDGLDWLRQSRZHULVDSSUR[LPDWHO\ KDOI WKDW LQ WKH ILUVW :LWK D GHFUHDVH LQ WKH UDGLXV RI FXUYDWXUH RI WKH PLUURU WKH HIILFLHQF\ RI WKH */ $( LQFUHDVHV IDVWHU WKDQ WKHHIILFLHQF\RI*/WKHUDGLDWLRQSRZHUDWDGLYHUJHQFHFORVH to the diffraction limit (ș  ± PUDG  LV ± WLPHV JUHDWHU in the first case. Therefore, in order to obtain a relatively powerful qualitative beam of radiation in the operating mode of CVL with a single mirror, it is more advantageous to use long AEs. But the PD[LPXPHIILFLHQF\RIWKHORQJ$(LVDFKLHYHGZKHQWKH\DUHXVHG DV D SRZHU DPSOLILHU LQ WKH 02±6)&±3$ ODVHU V\VWHPV Research results and analysis. The dependence of the average UDGLDWLRQ SRZHU DW WKH RXWSXW RI WKH &9/6 ZLWK WKH .ULVWDOO */ ($( DV WKH 3$ RQ WKH WHPSRUDO GHWXQLQJ RI WKH OLJKW SXOVH 02 UHODWLYH WR WKH SXOVH RI WKH 3$ ZLWK WKH UDGLXV RI FXUYDWXUH RI WKH FRQYH[ PLUURU R   FP >@ LV VKRZQ LQ )LJ 7KH UDGLDWLRQ power in the isolated (by means of the SFC) qualitative beam of WKH 02 DW WKH LQSXW RI WKH 3$ ZDV  : DW WKH RXWSXW ZLWK WKH 3$ VZLWFKHG RII  LW ZDV  : :LWK WKH RSWLPDO DGMXVWPHQW RI WKH CVLS (detuning zero), the output power of the radiation was 55 : RI ZKLFK  : LV WKH SRZHU WDNHQ IURP WKH 3$ ,Q WKH VDPH

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FRQGLWLRQV WKH SRZHU WDNHRII LQ WKH FDVH RI */ ZDV DERXW  :7KXVDQLQFUHDVHLQWKHOHQJWKRIWKHGLVFKDUJHFKDQQHOE\ times led to an increase in the energy capacity by a factor of 1.7. $QDGGLWLRQDOLQFUHDVHLQWKHUDGLDWLRQSRZHUZLWKWKH$(*/' is associated with the improvement of the electrical matching of the KLJKYROWDJHPRGXODWRURIQDQRVHFRQGSXPSSXOVHVZLWKDQH[WHQGHG AE and a relative increase in the volume of the active medium due to the establishment of a more uniform temperature distribution along the discharge channel. As can be seen from Fig. 4.32, the output power of the radiation is very sensitive to the temporal detuning. )RU H[DPSOH ZKHQ WKH GHWXQLQJ WLPH LV  QV WKH SRZHU LV UHGXFHG E\±7KHUHIRUHLQRUGHUWRPDLQWDLQWKHV\VWHPLQDQRSWLPDO mode, the two-channel power source must provide stable parameters of the pump pulses and a high degree of their synchronization. Figure 4.33 shows the dependence of the average radiation power (1 RIWKH&9/6DQGWKHSRZHUWDNHRIIZLWKWKH3$2) on the power DW WKH LQSXW RI WKH 3$ 7KH SRZHU RI WKH UDGLDWLRQ DW WKH LQSXW RI WKH3$YDULHGLQWKHUDQJHIURPWR:E\FKDQJLQJWKHUDGLXV RI WKH FRQYH[ 02 PLUURU IURP  WR  FP$W WKH VDPH WLPH WKH GLYHUJHQFH RI WKH RXWSXW EHDP RI WKH &9/6 YDULHG ZLWKLQ ± mrad. As a result, the output power of the system increased from WRZDWWVDQGWKHSRZHUUHPRYHGIURPWKHDPSOLILHUZDVIURP WRZDWWV$WWKHPD[LPXPUDGLDWLRQSRZHUWKHHIILFLHQF\RI WKH 3$ EDVHG RQ WKH LQSXW SRZHU LQ WKH$( ZDV  ,Q WKH PRGH RI RSHUDWLRQ RI 02 ZLWK WKH WHOHVFRSLF 85 DW 0   DQG WKH SRZHU DW WKH LQSXW RI WKH 3$  : WKH RXWSXW P rad, W

- 20

0

20

ns

Fig. 4.32. Dependence of the average radiation power of the copper vapour laser V\VWHP 02 $( */ ±6)&±3$ $( */(  DW D UDGLXV RI FXUYDWXUH RI WKH FRQYH[ PLUURU RI WKH 02 R   FP IURP WKH GHWXQLQJ WLPH RI WKH OLJKW VLJQDO RI WKH 02 ZLWK UHVSHFW WR WKH 3$ VLJQDO

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P rad, W 60

50~ 0

2

4

6

P 8inx ,, BT P W

Fig. 4.33. Dependence of the average radiation power (1) of the CVLS of the type 02$(*/ ±6)&±3$$(*/( ZLWKRQHFRQYH[PLUURULQWKH02DQG WKHGHSHQGHQFHRIWKHSRZHUWDNHRIIZLWKWKH3$2) on the radiation power at the LQSXW RI WKH 3$

SRZHU RI WKH &9/6 UDGLDWLRQ UHDFKHG DERXW  : GLYHUJHQFH  PUDG SUDFWLFDOHIILFLHQF\8QGHUWKHVDPHFRQGLWLRQVWKHODVHU V\VWHP LQ ZKLFK ERWK WKH 02 DQG WKH 3$ XVHG WKH */$( KDG DQ RXWSXW SRZHU RI DERXW  : DQG D SUDFWLFDO HIILFLHQF\ RI  >@)URPDFRPSDULVRQRIWKHVHGDWDLWIROORZVWKDWWKHLQFUHDVHLQ WKHRXWSXWSRZHURIWKH&9/6E\DIDFWRURI LVDFKLHYHG E\ LQFUHDVLQJ WKH SRZHU FRQVXPSWLRQ E\ RQO\  Investigations of CVLS of the MO–SFC–PA type with the telescopic UR and two elongated AE GL-201E as PA7KH 02 RI WKLV &9/6 used a telescopic UR with an increase of M   DQG D VHDOHG$( .XORQ */ ZLWK DQ DYHUDJH UDGLDWLRQ SRZHU RI : ,Q WKH ILUVW H[SHULPHQW WZR$(V */' ZHUH XVHG LQ WKH 3$ WR LQFUHDVH WKH RXWSXWSRZHURIWKH&9/67KHSXPSLQJRIERWK$(V*/(ZDV FDUULHGRXWIURPDWZRFKDQQHOV\QFKURQL]HGODPSSRZHUVXSSO\,3/ ±ZLWKD35)RIN+]7KHSRZHURIWKHODVHUV\VWHPZLWK WZR $(V */( DV WKH 3$ LQFUHDVHG WR  : WKH RXWSXW SRZHU RI WKH ILUVW 3$ ZDV  :  7KH GLYHUJHQFH RI WKH UDGLDWLRQ EHDP ZDV  PUDG WKH HQHUJ\ LQ WKH SXOVH ZDV  P- WKH SXOVH SHDN  SRZHUN:P W/IJpulse, where W is the energy in the pulse, IJpulse is the pulse duration at half the height). The practical efficiency of WKHV\VWHPZDVWKHHIILFLHQF\RIWKHDPSOLILFDWLRQVWDJHZDV WKHHIILFLHQF\RIWKHLQGLYLGXDO$(*/(ZDVDERXWWZLFH DV KLJK ±  :KHQWZR*/($(VZHUHXVHGDVWKH3$WKHRXWSXWSRZHU RIWKHODVHUSXOVHZDVZDWWVDWN+]35)GLYHUJHQFHPUDG SXOVHHQHUJ\P-SHDNSRZHUN:SUDFWLFDOV\VWHPHIILFLHQF\

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 ZKLOH WKH DPSOLILFDWLRQ VWDJH ZDV  WKH HIILFLHQF\ RI D VHSDUDWH */($( UHDFKHG  7KH $( */( ZDV SXPSHG IURP WK\UDWURQ SRZHU VRXUFHV in which the high-voltage pulse modulators used powerful waterFRROHGWK\UDWURQVɌ*,ZLWKVWDELOL]HGKHDWLQJRIDK\GURJHQ generator and a cathode. The voltage of the feeding three-phase QHWZRUNZDVVWDELOL]HGZLWKWKHKHOSRIDVWDELOL]HURIWKH&7&0 type. The diameter and length of the discharge channel of the AE ZHUH  DQG  PP UHVSHFWLYHO\ 7KH SRZHU FRQVXPSWLRQ IURP WKH SRZHU VRXUFH UHFWLILHU IRU RQH $( ZDV  N: IRU WKH VHFRQG ±  N: The attained values of the output radiation power in the CVLS ZLWKWZR$(V*/(DQGWZR$(V*/(DVWKH3$DQG : DUHQRWOLPLWLQJ$IXUWKHULQFUHDVHLQSRZHUFDQEHREWDLQHG by antireflecting the output windows of the AE, reducing the losses in the rotary mirrors, improving the characteristics of the pump current pulses, and temporarily matching the duration of the signals RIWKH02DQGWKH3$:KHQXVHGLQVWHDGRIWKH$(.XORQ*/ .ULVWDOO*/WKHUDGLDWLRQSXOVHVRIZKLFKKDYHDORQJGXUDWLRQ RIQVIJpulse§QV WKHSRZHUSLFNXSIURPRQH$(*/' (IJ pulse§QV KDVLQFUHDVHGXSWR:7RLQFUHDVHWKHGXUDWLRQRI WKH 02 SXOVH GLIIHUHQW RSWLFDO GHOD\ OLQHV FDQ EH XVHG )LJXUH shows the delay line consisting of four flat reflecting mirrors. The LQFUHDVH LQ WKH GXUDWLRQ RI WKH 02 VLJQDO ZLWK WKH */ $( E\ QVREWDLQHGXVLQJWKLVOLQHUHVXOWHGLQDQLQFUHDVHLQWKHV\VWHP RXWSXW E\ DSSUR[LPDWHO\  CVLS of the MO–PA type with several amplifying AEs. It is possible to substantially increase the radiation power of the CVLS RI WKH 02±3$ W\SH E\ LQFUHDVLQJ WKH QXPEHU RI DPSOLI\LQJ$(V LQ WKH 3$ +RZHYHU ZLWK ORVVHV DW WKH H[LW ZLQGRZV RI $(V FDXVHG E\ )UHVQHO UHIOHFWLRQ  IURP HDFK ZLQGRZ IDFH  LW LV SRVVLEOH that with a relatively small number of series-connected AEs in the 3$ WKH DGGLWLRQ RI WKH QH[W$( KDUGO\ LQFUHDVHV WKH WRWDO UDGLDWLRQ power. Such losses can be reduced by two-sided antireflecting output windows of the AE. The radiation power of such a multimodal CVLS LV WKH VXP RI WKH SRZHUV RI WKH LQGLYLGXDO $(V RI WKH 3$ DQG WKH 02

P&9/6

P  P  P  !  Pn  Pn ,

(4.21)

where P  LV WKH UDGLDWLRQ SRZHU IURP WKH 02 n is the number of

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)URP 02 Fig. 4.34. Variant of the optical system for increasing the duration of the pulses of WKH UDGLDWLRQ RI WKH 02 1 ± EHDP VSOLWWHU SODWH 2±5 ± IODW PLUURUV

$(VLQWKH3$Pi is the radiation power from the i-th AE, i n, P02 ·W w2 n1 ,

P

(4.22)

where IJ w is the transmittance of one window of the AE, P 02 is the UDGLDWLRQ SRZHU RI WKH 02 DW IJ w   (4.23) P P3$ ·W w2 n1 ,

P3$ ·W w2 n3 ,

(4.24)

Pn

P3$W w3 ,

(4.25)

Pn

P3$W w3 ,

(4.26)

P

where P 3$ is the radiation power of one AE at IJ w   6XEVWLWXWLQJ H[SUHVVLRQV  í  LQWR WKH IRUPXOD   we have:

P&9/6

P02W w2 n1  P3$ .(W w2 n1  W w2 n3  !  W w3  W w ),

(4.27)

where W w  W w  ...  W w  W w ±LQFUHDVLQJJHRPHWULFSURJUHVVLRQ 2 with the denominator q W w . As a result, a relatively simple formula is obtained for calculating the output power of the CVLS radiation, FRQVLVWLQJ RI RQH 02 DQG n LGHQWLFDO$(V LQ WKH 3$ 2 n 1

2 n 3

3

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P02W w2 n1  P3$

P&9/6

W w (1  W w2 n ) . 1  W w2

(4.28)

Since IJ w < 1, then for a large number of the amplifying AEs (n ĺ ’  WKH H[SUHVVLRQ   WHQGV WR WKH YDOXH

P&9/6

P3$

Ww . 1  W w2

The need to reduce losses on the AE windows can be demonstrated E\WKHH[DPSOHZKHQWKHUHLVQRDQWLUHIOHFWLRQDQGIJ w ,QWKLV FDVHWKHPD[LPXPRXWSXWSRZHURIWKHV\VWHPGRHVQRWH[FHHGP3$: P&9/6

P3$

 | 6 P3$ .   2

Figure 4.35 shows the dependences of the normalized radiation power of the laser system (P out/P 3$) on the number of amplifying AEs, calculated from formula (4.28). It is seen that the greater the loss on the windows, the stronger the dependence deviates from the linear one (which corresponds to the idealized case of zero losses (IJ w    DQG JRHV IDVWHU WR VDWXUDWLRQ A new generation of industrial sealed-off self-heating AEs of WKH VHULHV .ULVWDOO */$ .ULVWDOO /7&X  */% .ULVWDOO /7&X  DQG */& .ULVWDOO /7&X  VHH7DEOH   >  ±@ ZLWK D JXDUDQWHHG OLIHWLPH RI PRUH WKDQ  KRXUV LV SURGXFHG ZLWK DQ DQWLUHIOHFWLQJ H[LW ZLQGRZ IJ w !   ,I ZH VHW IRU H[DPSOH WKH RXWSXW UDGLDWLRQ SRZHU RI WKH &9/6 DW WKH OHYHO RI  RI WKH SRZHU DW D WUDQVPLWWDQFH IJ w   WKHQ LQ WKH FDVH RI the antireflecting windows with IJ w   LW LV DGYLVDEOH WR SXW QR more than 12 AEs in one amplifying optical line. If the AE output windows are used without superradiance, i.e., with a transmittance IJ w   WKHQ DW WKH LQGLFDWHG OHYHO   LW PDNHV VHQVH WR XVH QR more than three AEs. The development and application of multi-module, high-power &9/6 RI WKH 02±3$ W\SH RQ WKH EDVLV RI LQGXVWULDO VHDOHGRII$(V Kristall, produced by the Istok Company, are carried out at the Kurchatov Institute (Moscow), Medical Sterilization Systems LLC 2GLQWVRYR 0RVFRZ 5HJLRQ  DQG WKH Institute of Semiconductor 3K\VLFV 1RYRVLELUVN 

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IJw = 1

10 8 6

4 2 0

2

4

6

8

10 12 14 n

Fig. 4.35. The dependence of the normalized radiation power of the laser system 02±3$ P out/P 3$) on the number of amplifying AEs (n).

Each amplification path of CVLS usually includes two or three $(V */% .ULVWDOO /7&X  RU */& .ULVWDOO /7&X  7KHPRVWFRPPRQO\XVHG02LVWKH$(*/$.ULVWDOO/7&X  ZLWK D WHOHVFRSLF 85 RU OHVV RIWHQ WKH$( */% LQ WKH UHJLPH ZLWK RQH FRQYH[ PLUURU ,I IRU H[DPSOH WKUHH $(V */%V DUH XVHG DV 3$V HDFK RI ZKLFK SURYLGHV D SRZHU WDNHRII RI DERXW  : DQG WKH $( RI  $ DV WKH 02 ZLWK D SRZHU LQ D TXDOLWDWLYH EHDPRI:DQGZLWKDWUDQVPLWWDQFHRIWKHDQWLUHIOHFWLQJZLQGRZV IJ w   WKHQ WKH RXWSXW SRZHU RI WKH V\VWHP LQ DFFRUGDQFH ZLWK the formula 4.28 is PCVLS  ā 7  

  6 :   2

:KHQ WKUHH $(V */& DUH XVHG DW D SRZHU WDNHRII IURP DQ $( RI DERXW :  WKH RXWSXW SRZHU RI WKH &9/6 XQGHU WKH VDPH FRQGLWLRQV DV IRU WKH */% $( VKRXOG EH  : +RZHYHU it should be emphasized that these values of the laser radiation power can be achieved only under the condition of ideal spatial and temporal matching of all the AEs entering into it.

4.7. Investigation of the properties of the active medium of a pulsed CVL using CVLS ,Q WKLV SXOVHG &9/6 LWV 02 XVHG WKH $( .XORQ RI WKH */(

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model with a telescopic type of UR with an increase of M   ZDVXVHGLQWKH3$±LQRQHFDVH$(*/(LQWKHRWKHUDPRUH SRZHUIXO $( */, 7DEOH   2QH RI WKH PDLQ FKDUDFWHULVWLFV RI D ODVHU V\VWHP IRU D JLYHQ 35) DV ZDV VKRZQ DERYH LV WKH dependence of the output radiation power on the synchronization of WKH SXOVHV RI WKH 02 UHODWLYH WR WKH SXOVHV RI WKH 3$ ,Q )LJ  such a dependence of the radiation power on the temporal detuning RI WKH OLJKW VLJQDO RI WKH 02 ZLWK UHVSHFW WR WKH OLJKW VLJQDO RI WKH 3$LVSUHVHQWHGIRUWKH&9/6XVLQJWKHVDPH$(*/(LQWKH02 DQG 3$ 35)  N+]  LQ )LJ  ± IRU D PRUH SRZHUIXO &9/6 ZLWK WKH XVH RI$( */, LQ WKH 3$ 35)  N+]  :LWK D ]HUR WHPSRUDO GHWXQLQJ RI WKH VLJQDOV RI WKH 02 DQG 3$ WKHRXWSXWSRZHURIWKHUDGLDWLRQDQGWKHHIILFLHQF\DUHPD[LPDO7KH PD[LPXP YDOXH RI WKH DYHUDJH UDGLDWLRQ SRZHU RI WKH &9/6 ZLWK WKH$( */( LQ WKH 02 DQG 3$ LV ±: DW DQ HIILFLHQF\ RI  )LJ   ZLWK DQ$( LQ WKH 3$ ± ±: DW DQ HIILFLHQF\ RI  )LJ  :KHQ WKH OLJKW VLJQDO RI WKH 02 LV WHPSRUDOO\ GHWXQHGERWKLQWKHGLUHFWLRQRIWKHGHOD\IURPWKH3$VLJQDODQGLQ the direction of its advance, the radiation power curve, due to the VKRUWWLPHRIH[LVWHQFHRISRSXODWLRQLQYHUVLRQLQWKH$0IDOOVTXLWH sharply. At detuning within ±25 ns, the radiation power is reduced WR WKH OHYHO RI WKH LQSXW VLJQDO IURP WKH 02 ±: 7KH VLJQ µ±¶ FRUUHVSRQGV WR WKH GHOD\ µ¶ ± WR DGYDQFH ,I WKH 02 VLJQDO ODJV EHKLQG E\ PRUH WKDQ ± QV WKLV VLJQDO LV FRPSOHWHO\ DEVRUEHG LQWKH$0RIWKH3$GXHWRDVKDUSLQFUHDVHLQWKHFRQFHQWUDWLRQRI copper atoms with populated metastable levels at the decay of the GLVFKDUJHFXUUHQWSXOVH:KHQWKH02VLJQDODGYDQFHVE\±QV its partial absorption takes place, and it reaches a minimum power YDOXH : DW t   QV  The appearance of a zone of weak absorption is due to the population of metastable levels of a part of copper atoms at the initial stage of the development of pump current pulses (discharges). :KHQDGYDQFLQJIRUDWLPHORQJHUWKDQQVWKHDFWLYHPHGLXPRI WKH3$EHFRPHVSUDFWLFDOO\WUDQVSDUHQWIRUWKHVLJQDORIWKH02,Q WKLV PRGH WKH VLJQDO SRZHU RI WKH 02 DW WKH RXWSXW RI WKH 3$ ZDV a:WKHVLJQDOVWUHQJWKRIWKH02VLJQDODWWKHLQSXWLVa:  3DUWRIWKHSRZHU±DERXW: ±ZDVORVWRQWKHZLQGRZVRI WKH$(RIWKH3$WKHRWKHUSDUW±: ±SUREDEO\DEVRUEHG by its active medium. The latter testifies that the active medium of WKH 3$ LQ WKH LQWHUSXOVH SHULRG DW WKH 35) RI ± N+] LV QRW completely restored.

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FRPSHQVDWHG E\ LQWURGXFLQJ LQWR WKH7036 D VHFRQG FRPSRQHQW RI the magnetic compression of the pulses. Thus, at the same time, a significant reduction in energy losses in the thyratron commutator is achieved and the pump efficiency remains at the same level. The decrease in losses in the thyratron was confirmed during the H[SHULPHQW E\ D GHFUHDVH LQ WKH WHPSHUDWXUH RI WKH WK\UDWURQ DQRGH IURP  WR ƒ& ZKLOH WKH FRQWULEXWLRQ RI WKH ILODPHQW HQHUJ\ RI WKH WK\UDWURQ FDWKRGH WR WKH DQRGH WHPSHUDWXUH ZDV DERXW ƒ& The circuitry solutions adopted in the development of the industrial laser made it possible to reduce not only the switching losses in the thyratron, but also to increase the reliability of the laser elements as a whole and to ensure the stability of the output radiation parameters. 7KH LQGXVWULDO &9/ .XORQ  ZLWK VHDOHGRII VHOIKHDWLQJ $( PRGHO */' 1R    ZLWK DQ LQFUHDVHG FRQWHQW RI DFWLYH copper substance was subject to long-term resource tests. CVL WHVWV ZHUH FDUULHG RXW ZLWK DQ KRXU F\FOLF PRGH DW  N+] 35) DQG DQ LQLWLDO DYHUDJH UDGLDWLRQ SRZHU RI  ZDWWV 'XULQJ  hours, the average power of radiation decreased from 14.5 to 7.5 :$V D WK\UDWURQ FRPPXWDWRU LQWKH70),ODVHUDWK\UDWURQ RIWKH 7*,. WHWUDKHGUDO GHVLJQ ZDV XVHG 'XULQJ WKH OLIH WHVWV ZKLFK ODVWHG XS WR  KRXUV QR IDLOXUH ZDV GHWHFWHG LQ WKH ODVHU operation. The dependence of the average radiation power for this CVL .XORQ  ZLWK$( 1R   RQ WKH RSHUDWLQJ WLPH LV VKRZQ LQ Fig. 5.16 (curve 1). Here, for comparison, analogous dependences ZLWK$( */( 1R   FXUYH 2  DQG */' .XORQ /7 &X  1R   FXUYH   REWDLQHG GXULQJ EHQFK WHVWV DUH DOVR shown.

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Table 5.3. Radiation power and efficiency of industrial metal vapour lasers of the Kulon series Average radiation SRZHU:

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Copper Vapour Lasers and Copper Vapour Laser Systems

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Table 5.4. The main parameters of industrial impulse lasers on metal vapours of the Kulon series 3DUDPHWHU

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)LJXUH  VKRZV WKH VWUXFWXUDO EORFN GLDJUDP )LJ  WKH IXQFWLRQDO HOHFWULFDO GLDJUDP RI WKH LQGXVWULDO &9/ .XORQ  DQG .XORQ  The power of industrial lasers is provided by a single-phase DOWHUQDWLQJFXUUHQWQHWZRUNZLWKDYROWDJHRI“9IUHTXHQF\ “+]7KHSRZHUFRQVXPSWLRQRIWKH&9/IURPWKHJULGGRHV QRW H[FHHG  N:7KH SRZHU VRXUFH LQ WKH &9/ SURYLGHV DXWRPDWLF output to the operating mode and maintenance of the set value of the input power in the AE during long-term operation in both continuous and cyclic modes, as well as electronic protection over the air and WKH H[WHUQDO QHWZRUN The basic electrical circuit of the high-voltage generator of QDQRVHFRQGSXOVHVIURPWKH$($ SXPSLQJFKDQQHODQGWKHORZ power additional generator of the nanosecond modulation channel $ RIWKH&9/.XORQDQG.XORQLQWHUPVRIWKHFRPSRVLWLRQ of the elements and the physical principle of operation are identical with each other and with the high-voltage pulse generator of a VLQJOHFKDQQHO EDVH &9/ .XORQ  7KH SUHVHQFH RI WKH DGGLWLRQDO PRGXODWLRQ FKDQQHO $  DQG WKH FKDQQHO V\QFKURQL]DWLRQ GHYLFH $ LQWKH&9/V.XORQDQG.XORQDOORZWRSHUIRUPSRZHU control according to a predetermined algorithm, including monopulse DQG SDFNHW UDGLDWLRQ PRGXODWLRQ ZKLFK VLJQLILFDQWO\ H[SDQGV WKH possibilities of their practical application. The physical essence of the CVL operation with radiation modulation with sealed-off self-heating AEs is as follows. In the operation of CVL with an additional pulse and constant energy input in the AE under conditions of stabilized plasma parameters, changing WKHGHOD\EHWZHHQSXOVHVRIWKHPDLQSXPSFXUUHQWH[FLWDWLRQ DQG additional low-power current pulses, it is possible to control the HQHUJ\ DQG VSDFH±WLPH FKDUDFWHULVWLFV RI UDGLDWLRQ JHQHUDWLRQ  DQG wide limits, as well as chromaticity. In order to provide the generation mode in the laser, an additional ORZSRZHU FXUUHQW SXOVH LV IRUPHG DIWHU WKH PDLQ H[FLWDWLRQ SXOVH and an additional pulse is formed in front of the main pulse to SURYLGH WKH PRGH RI H[WLQFWLRQ RI WKH JHQHUDWLRQ 7KH HQHUJ\ RI additional current pulses (formed by a low-power generator) should be sufficient only for the population of metastable (lower) laser levels RIWKHDFWLYHVXEVWDQFH±FRSSHUDWRPV$QDGGLWLRQDOLPSXOVHLQWKLV case determines only the processes of populating metastable levels, EXW GRHV QRW DIIHFW WKH SURFHVVHV RI WKHLU UHOD[DWLRQ LQ WKH SODVPD in the interimpulse period, i.e., an additional pulse must be near the

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PDLQ H[FLWLQJ FXUUHQW SXOVH 1DWXUDOO\ WKH HIIHFWLYH FRQWURO RI WKH output energy characteristics of the laser is provided to the greatest H[WHQWZKHQWKHWLPHGLIIHUHQFHEHWZHHQWKHDGGLWLRQDOFXUUHQWSXOVH DQG WKH PDLQ SXOVH WKH H[FLWDWLRQ SXOVH  LV OHVV WKDQ WKH OLIHWLPH RI WKH PHWDVWDEOH OHYHOV :LWK WKH H[SHULPHQWDO RSWLPL]DWLRQ RI WKH &9/WKHLQGLFDWHGWLPHGHWXQLQJZDVQRPRUHWKDQȝV,QDGGLWLRQ from the point of view of stabilizing the parameters of the active medium plasma, this is the optimum operating mode of CVL, when the power consumed from the electric network during generation (with a lagging additional pulse) is equal to the power consumed by WKHODVHULQWKHFDVHRIH[WLQFWLRQRIWKHJHQHUDWLRQZLWKDQDGYDQFHG additional pulse). This mode is achieved by adjusting the phase and the amplitude of the additional current pulse. Figure 5.21 shows the

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oscillograms of the additional and main pulses of the pump voltage H[FLWDWLRQ DWWKHHOHFWURGHVRIWKH$(&9/LQWKHTXHQFKLQJPRGHV (upper oscillogram) and generation (lower), indicating the color time zones of the AM (see section 4.7). 7KH UHVXOWV RI H[SHULPHQWDO WHVWV RI LQGXVWULDO &9/V .XORQ  DQG .XORQ  RQ WKH EDVLV RI WKH DERYH FRQWUROOHG WZRFKDQQHO 3, of nanosecond pulses have shown that with optimized parameters of WKHSXPSSXPSLQJSXOVHVWKHPD[LPXPYDOXHVIRUERWKWKHUDGLDWLRQ power and efficiency are achieved, modulation of radiation and SUDFWLFDOO\ WURXEOHIUHH RSHUDWLRQ RI WKH GHYHORSHG WZRFKDQQHO 3, In the usual regular pulsed-periodic frequency operation of the CVL .XORQDQG.XORQLHLQWKHDEVHQFHRIUDGLDWLRQPRGXODWLRQ DWWKH35,RI±N+]WKHDFKLHYHGYDOXHVRIWKHDYHUDJHUDGLDWLRQ SRZHU ZLWK WKH VHDOHG VHOIKHDWLQJ $( */( .XORQ /7&X  ZHUH±:ZLWK$(*/,.XORQ/7&X ±±:DWWKH HIILFLHQF\ RI WKH UHFWLILHU RI WKH SRZHU VRXUFH ± The pulsed switch in the high-voltage generator of the main FKDQQHOLVWKHK\GURJHQWK\UDWURQ7,*.LQWKHJHQHUDWRURI WKHDX[LOLDU\FKDQQHO7*,7KHPD[LPXPSRZHUFRQVXPSWLRQ from the rectifier of the power source in the operating mode is not PRUH WKDQ  N: WKH PD[LPXP RSHUDWLQJ YROWDJH DW WKH DQRGH RI the thyratron of the main channel is 12 kV. The non-linear forming line of the main channel is made up of a two-link, and the non-linear IRUPLQJ OLQH RI WKH DX[LOLDU\ FKDQQHO LV VLQJOHHQGHG SRVLWLRQV  DQG   7KH LQGXFWDQFHV RI WKH DQRGH UHDFWRUV RI WKH PDLQ DQG DX[LOLDU\ FKDQQHOV DUH  ȝ* $Q DGMXVWDEOH KLJKYROWDJH SRZHU supply (item 12) is a constant voltage source on uncontrolled diodes and a controlled single-ended resonant converter, at the output of which a high-voltage transformer-rectifier unit is installed. The charging time of capacitive energy storage devices of nonlinear DUWLILFLDOIRUPLQJOLQHVLVȝV$GMXVWDEOHGHOD\OLQHVNH\VDQG   SURYLGH D UDQJH RI WLPH FRQWURO RI SXOVHV XS WR  QV 7KH UDQJHRIDGMXVWPHQWRIWKHH[FLWDWLRQFXUUHQW DPSOLWXGHRIWKHPDLQ FKDQQHOXSWR$IRUDGXUDWLRQRILWVIURQWLVQRPRUHWKDQQV WKHYROWDJHDPSOLWXGHLVXSWRN97KHDPSOLWXGHRIWKHDX[LOLDU\ FKDQQHOFXUUHQWSXOVHLVXSWR$WKHYROWDJHDPSOLWXGHLVXSWR N9 7KH GXUDWLRQ RI WKH H[FLWDWLRQ SXOVH RI WKH PDLQ FKDQQHO DORQJ WKHEDVHLVDERXWQVWKHDX[LOLDU\SXOVHGXUDWLRQLVXSWRQV :LWK WKHVH RSWLPL]HG SDUDPHWHUV RI WKH PDLQ DQG DGGLWLRQDO SXPS SXOVHV H[FLWDWLRQ  LQ WKH &9/V .XORQ  DQG .XORQ  WKH PD[LPXPSRZHURIUDGLDWLRQDQGWKHHIILFLHQF\ZHUHUHDFKHGDWWKH

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working pulse repetition frequencies. The change in the response time of adjustable delay lines (items 14 and 15) and the formation, according to a predetermined law, of single pulses at the output of the controller (item 22) allows the high-speed pulse modulation of laser radiation to be accurate to one pulse, to implement any of their sequence, to set certain values of the impulse energy, etc. And more importantly, the design of the CVL provides for the possibility of FRQWUROOLQJWKHRSHUDWLQJPRGHVIURPDQH[WHUQDOSHUVRQQHOFRPSXWHU 7KHVHDGYDQWDJHVPDNHLWSRVVLEOHWRXVHSXOVHG&9/VDQG*9/V DQG &*9/V EDVHG RQ WKHP DV ZHOO DV RWKHU ODVHUV EDVHG RQ VHOI terminating transitions, practically in all fields of science, engineering DQGPHGLFLQH)RUH[DPSOHRQHRIWKHDGYDQFHGDSSOLFDWLRQVLVWKH technology of microprocessing of metallic materials. 7KHXVHRIWKH&9/.XORQDQG.XORQDVSDUWRIDXWRPDWHG laser technological installations (ALTI) such as Karavella-2 and Karavella-2M allows precise microprocessing of almost any metal and a wide range of non-metallic materials. The CVLs of the Kulon series are also effective for precision marking and deep engraving of parts and drawing images in volumes of transparent media (glass, quartz, sapphire).

5.3. Two-channel Karelia CVLS with high quality of radiation 7KH .DUHOLD WZRFKDQQHO &9/ ZDV GHYHORSHG LQ  7KLV &9/6 ZRUNV DFFRUGLQJ WR WKH 02±6)&±3$ VFKHPH 7KH DLP RI WKH development was to create a CVL with an average radiation power LQ D EHDP RI GLIIUDFWLRQ TXDOLW\ RI DW OHDVW  :$W WKH EHJLQQLQJ RI WKH GHYHORSPHQW D ODUJH YROXPH RI WKHRUHWLFDO DQG H[SHULPHQWDO studies of the energy, spatial and temporal characteristics of the laser radiation was carried out, most of which is presented in the Chapters  DQG  DQG WKH ILUVW LQGXVWULDO VHDOHGRII$( .ULVWDOO */ ZLWK D WRWDO DYHUDJH RXWSXW SRZHU DW HIIHFWLYH SXPSLQJ RI  : DQG JXDUDQWHHG XS WR  K >±@ ZDV FRQVWUXFWHG %\ WKLV WLPH it became clear that, on the basis of the totality of its properties, te CVL is an almost ideal tool not only for pumping wavelengthWXQDEOHODVHUVRQG\HVROXWLRQVXVHGLQWHFKQRORJLFDOFRPSOH[HVIRU isotope separation, but also for precise microprocessing of a number RI PDWHULDOV XVHG IRU H[DPSOH IRU HOHFWURQLF SURGXFWV The Karelia CVL includes a two-channel Karelia radiator GHVLJQDWLRQ DFFRUGLQJ WR 78±,/*,  DQG D WZRFKDQQHO

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IRU SURGXFLQJ KLJKSRZHU DQG KLJKTXDOLW\ UDGLDWLRQ EHDPV >± @ 7KH VHDOHGRII VHOIKHDWLQJ */ $( LV XVHG DV DQ $( LQ WKH 02 DQG 3$ RI WKH .DUHOLD UDGLDWRU SRVLWLRQV  DQG  LQ )LJ   The AEs are installed in cylindrical double-wall water-cooled steel KHDWVLQNVLWHPVDQG ZLWKDQLQWHUQDOGLDPHWHUHTXDOWRPP The AEs are attached to the heat sinks through water-cooled steel half-rings (item 5), mounted directly on its electrode assemblies, and fluoroplastic rings-isolators (6), located between the half-rings and the heat sink. The heat sinks are not only a load-bearing structure for the AE, but also perform the function of a reverse current conductor. $ WHOHVFRSLF W\SH 85 RU RQH FRQYH[ PLUURU LV XVHG LQ WKH 02 IRU the formation of a qualitative beam, . In the design of the radiator Karelia there are two possibilities for WKHH[HFXWLRQRIWKH02UHVRQDWRUDQGDFFRUGLQJO\WZRYHUVLRQVRI the SFC. Figure 5.26 a shows the optical scheme of the radiator in the mode of operation of a laser with the telescopic UR, Fig. 5.26 b ± ZLWK RQH FRQYH[ PLUURU

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The geometric dimensions of the mirrors (the radius of curvature R and the diameter of the mirror D 3) are indicated in the caption to Fig. 5.26. The increase in the telescopic UR is M :KHQXVLQJ VXFKDQ85WZRQDUURZO\IRFXVHGEHDPVDUHIRUPHG±ZLWKș geom  PUDGDQGșdif PUDG$FRQYH[PLUURUZLWKDVLQJOHPLUURU version has a radius of curvature of R   RU  FP ,Q WKLV FDVH D beam with a divergence ș lim RUPUDGLVIRUPHGEXWZLWKD more even distribution of the radiation intensity in the far zone and D KLJK VWDELOLW\ RI WKH SRVLWLRQ RI WKH D[LV RI WKH UDGLDWLRQ SDWWHUQ EHDP DQG WKH PDJQLWXGH RI WKH SXOVHG HQHUJ\ >±@ The SFC of the emitter is designed to suppress the incoherent EDFNJURXQG FRPSRQHQWV RI WKH RXWSXW UDGLDWLRQ RI WKH 02 DQG WR VSDWLDOO\ PDWFK WKH H[WUDFWHG TXDOLWDWLYH EHDP ZLWK WKH DSHUWXUH RI WKH GLVFKDUJH FKDQQHO RI WKH 3$ >   @ 7KH 6)& GLDSKUDJP ZKLFK FXWV RII WKH EDFNJURXQG FRPSRQHQWV RI WKH 02 radiation, is established in the waist of the qualitative beam. The use of a mirror collimator, and not a lens collimator, precludes the

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appearance of parasitic feedbacks between the optical elements of WKH6)&DQG0)02DFKURPDWLFDEHUUDWLRQV7RUHGXFHDVWLJPDWLVP WKH 6)& ZDV ORFDWHG SDUDOOHO WR WKH 02 DQG 3$ LQ VXFK D ZD\ WKDW WKHDQJOHVRIWKHHQWUDQFHDQGH[LWRIWKHEHDPZHUHPLQLPDO(DFK circuit of the resonator design corresponds to its optical elements of the SFC having certain geometric dimensions and radii of curvature. All elements of the optical system of the radiator are structurally integrated into one unit, which can be collected separately, preconfigured and then installed in the radiator. The load-bearing structure of this assembly is a three-rod frame made of aluminium alloy, on which transverse strips with mechanisms for aligning the PLUURUVRIWKHUHVRQDWRUFROOLPDWRUDQGURWDU\PLUURUVDUHIL[HG7KH VHDOHGRII $(V RI WKH 02 DQG 3$ DUH VWUXFWXUDOO\ FRQQHFWHG ZLWK 3)&V DQG DUH QRW UHTXLUHG WR EH UHSODFHG ZKHQ WKH RSWLFDO V\VWHP is adjusted. In order to prevent the occurrence of achromatic aberrations in a two-wave beam and to reduce the laboriousness of optical-mechanical SURFHVVLQJDOORSWLFDOHOHPHQWVDUHPLUURUV)LJ 7KHH[FHSWLRQ is the beam-splitting plane-parallel glass plate (item 33 in Fig.   DQG D JODVV VXEVWUDWH ZLWK DQ RXWSXW FRQYH[ PLUURU SDVWHG RQ it (position 2 in Fig. 5.25, a) in the telescopic UR. The plate and the substrate are made of K8 optical glass and are antireflective UHIOHFWLRQ FRHIILFLHQW OHVV WKDQ  LQ WKH \HOORZ±JUHHQ UHJLRQ RI the spectrum). The substrates for the mirrors are also made of K8 JODVV 7KH WUDGLWLRQDO WHFKQRORJLFDO SURFHVV RI RSWLFDO±PHFKDQLFDO processing makes it possible to manufacture optical parts of the required shape with a high quality of the surface. The reflective coating of mirrors is a multilayer dielectric film based on zinc sulphide and magnesium fluoride. Not all optical elements of the laser work under the same conditions, therefore their guaranteed operating time is different. This applies primarily to mirrors located on the side of the high-voltage cathode nodes of the AE. In a high-voltage electric field, suspended particles in the air acquire an electric charge and are deposited, PRVWO\ RQ QHDUE\ PLUURUV$OUHDG\ DIWHU  KRXUV RI RSHUDWLQJ WKH radiator under ordinary laboratory conditions, a diffusely reflecting dust layer is formed on the surface of the mirrors, which significantly reduces the output power and the radiation quality. To reduce the HIIHFW RI GXVW LW LV QHFHVVDU\ WR VHDO WKH VSDFH EHWZHHQ WKH H[LW windows of the AE and the mirrors. Note that the main security measure when working with mirrors is the isolation of their surface

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from direct physical contact with any solid and liquid bodies. Cleaning the surface can be done using medical cotton wool soaked in pure acetone or alcohol, and a squirrel art brush. The TI-3 power converter is used as a receiver for the laser power indicator, which is characterized by high operating parameters. The RSHUDWLQJ UDQJH RI 7,± LV  : WKH WLPH RI HVWDEOLVKPHQW RI WKHVWDWLRQDU\PRGHLVV7KHUDGLDWLRQWRWKHLQSXWRIWKHUHFHLYHU TI-3 (item 34 in Fig. 5.25) is fed from the beam splitter plate (item  LQVWDOOHGDWWKHRXWSXWRIWKH3$7KHUPDO(0)ZKLFKDSSHDUHG in the TI-3 power converter and is proportional to the power of the incident radiation, either goes directly to the indicator device IRU H[DPSOH WKH 0 PLOOLYROWPHWHU  RU VHUYHV DV D VLJQDO IRU introducing feedback into the power supply in order to maintain the radiation power at a given level. To cover the radiation beam at the output of the radiator, an electromechanical shutter with a traction electromagnet EU + LWHP  LQ )LJ   LV LQVWDOOHG DV D VKXWWHU KDYLQJ the following parameters: operating voltage and current 24 V, current $DYHUDJHVSHHGEHDPRYHUODSRIPVDVSUHDGLQJWLPHRI  PV 2YHUODSSLQJ RI WKH EHDP LQ WKH VKXWWHU LV GRQH ZLWK WKH KHOS RI D GXPE IODW PLUURU IL[HG LQ LW ZLWK D UHIOHFWLRQ FRHIILFLHQW ! (mirror diameter 35 mm). The electromechanical gate is inertial and in cannot be used in PDQ\FDVHVRI&9/DSSOLFDWLRQVIRUH[DPSOHLQWHFKQRORJLHVZKHUH operational control of the characteristics is required. For the purpose of increasing the speed, an electronic radiation power control circuit was created. The principle of operation of this scheme is based on the SDUWLDO RU WRWDO DEVRUSWLRQ RI 02 UDGLDWLRQ LQ WKH DFWLYH PHGLXP RI WKH3$ZKLFKLVDFKLHYHGE\FKDQJLQJWKHGHOD\WLPHRIWKHRSWLFDO VLJQDO RI WKH 02 ZLWK UHVSHFW WR WKH VLJQDO RI WKH 3$ &KDSWHU  6HFWLRQ   > @ 7KH GHOD\ WLPH IRU FRPSOHWH DEVRUSWLRQ GHSHQGVRQWKHH[FLWDWLRQFRQGLWLRQVRIWKHDFWLYH02DQG3$PHGLD DQGLVXVXDOO\DWOHDVW±QV7KXVZKHQWKHUDGLDWRULVSXPSHG IURP WKH WK\UDWURQ SRZHU VXSSOLHV ,3 WKH GHOD\ WLPH RI WKH 02 VLJQDOLQUHODWLRQWRWKHVLJQDORIWKH3$LVQRWOHVVWKDQQVZLWK D ODPS VRXUFH RI WKH 3OD] RU ,3/± W\SH QRW OHVV WKDQ  QV For full overlapping of the radiation beam, for safety reasons, D PHFKDQLFDO VKXWWHU±GDPSHU LWHP  LQ )LJ   ORFDWHG RQ WKH front panel of the radiator is used. The basis of the load-bearing structure of the radiator is a welded frame made of steel pipes of rectangular cross-section with

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GLPHQVLRQV RI  î  î  PP 2Q WKH EDVH RI WKLV IUDPH WKUHH ORQJ ,EDUV ZLWK D VHFWLRQ RI  î  PP IURP '7 DOXPLQLXP DOOR\ DUH IL[HG 7KH\ FRQWDLQ DOO WKH PDLQ HOHPHQWV RI WKH UDGLDWRU 023$6)&WKHRXWSXWEHDPVSOLWWHULQVXODWRUVIRUIDVWHQLQJKLJK voltage power cables, inlet and outlet chokes of the cooling system, power indicator receiver, electromechanical and mechanical gates, electrical interlocks and covers. The covers of the radiator not only determine its shape and aesthetic appearance, but also fulfill the function of protecting the ether from radio interference. The covers are made of 1.2 mm thick steel and overlap by 15 mm at the joints. The emitter is mounted on four supports, which allow to adjust WKHKHLJKWRIWKHRXWSXWEHDPZLWKLQ“PPDQGWKHRULHQWDWLRQRI LWV GLUHFWLRQ LQ VSDFH ZLWK DFFXUDF\ QRW ZRUVH WKDQ  PUDG 7KH02DQGWKH3$ZLWKF\OLQGULFDOKHDWVLQNVDUHDWWDFKHGWRWKH supporting structure by means of horizontal and vertical supports, ZKLFK FDQ EH DGMXVWHG KRUL]RQWDOO\ DQG YHUWLFDOO\ :KHQ LQVWDOOLQJ DQGUHSODFLQJWKH$(LQWKH02DQGWKH3$WKHDGMXVWDEOHVXSSRUWV DOORZ LI QHFHVVDU\ WR FRPELQH WKH JHRPHWULF D[HV RI WKH $( ZLWK WKH D[LV RI WKH RSWLFDO V\VWHP RI WKH UDGLDWRU 7KHPLUURUVRIWKH02DQGWKH6)&DVZHOODVWKHURWDU\PLUURUV DUHIL[HGLQWKHXQLILHGDOLJQPHQWPHFKDQLVPVZKLFKDOORZWRDGMXVW WKH RSWLFDO HOHPHQWV ZLWK D VXIILFLHQWO\ KLJK DFFXUDF\  UDG SHU RQH UHYROXWLRQ RI WKH DGMXVWLQJ VFUHZ ± LQ )LJ   The power emitted in the radiator, depending on the pumping FRQGLWLRQV RI WKH $( */ LV LQ WKH UDQJH ± N: ± ± N: IURP HDFK $( 7R H[FOXGH RYHUKHDWLQJ RI WKH $( DQG radiator components and associated negative consequences (decrease in longevity, deterioration in the stability of energy parameters and WKH SRVLWLRQ RI WKH D[LV RI WKH UDGLDWLRQ SDWWHUQ LQFUHDVH LQ WKH FODGGLQJWHPSHUDWXUH DIRUFHGZDWHUFRROLQJV\VWHPLVXVHG:DWHU carries away heat from the heaters of the AE, its end sections and the electromechanical shutter. The water flow is about 5 l/min with the pressure at the input of the system up to 2 atm. The temperature difference between the input and output of the cooling system is DSSUR[LPDWHO\ ƒ& To protect maintenance personnel from electric shock and laser radiation, blocking devices, warning signs and inscriptions, absorbing coatings are provided in the design. Electrical interlocks (item 37 in Fig. 5.25) are installed for each of the three removable covers RI WKH UDGLDWRU 2Q WKHVH VDPH FRYHUV WKHUH DUH VLJQV RI HOHFWULFDO

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GDQJHU 2Q WKH IDFHSODWH RI WKH UDGLDWRU DERYH LWV RXWSXW DSHUWXUH D ODVHU KD]DUG PDUN LV DIIL[HG DQG WKH DSHUWXUH RXWOHW  LWVHOI FDQ be overlapped by a mechanical shutter if necessary (item 36). The radiator has a protective earthing bolt with a ground sign on the labeled label (item 38 in Fig. 5.25), connections for water supply and drainage (drain and water labels). All the individual parts and FRPSRQHQWV RI WKH UDGLDWRU XQGHU WKH OLQLQJ DUH SDLQWHG EODFN ± WR reduce the level of scattered and re-reflected laser radiation. The energy parameters of the radiator are determined to D JUHDW H[WHQW E\ WKH W\SH RI SRZHU VRXUFH 7KH KLJK ORQJHYLW\ DQG UHSURGXFLELOLW\ RI WKH SDUDPHWHUV RI WKH $( */ DQG WKH UHOLDEOH UDGLDWRU ,/*, FUHDWHG RQ WKHLU EDVLV PDGH LW SRVVLEOH to objectively compare the parameters of the two-channel thyratron and lamp power supplies. Two samples of the Karelia CVL with thyratron power sources ,3 ZHUH PDQXIDFWXUHG DQG WHVWHG ,Q WKH ILUVW VDPSOH WKH KLJK voltage pump modulator of each power source was made in a GLUHFW HOHFWULF FLUFXLW LQ WKH VHFRQG ± WR LPSURYH WKH H[FLWDWLRQ HIILFLHQF\RIWKH$(±DFFRUGLQJWRWKHVFKHPHRIYROWDJHGRXEOLQJ and magnetic compression of current pulses. The triggering of the K\GURJHQ WK\UDWURQV 7*, RI WKH ,3 PRGXODWRUV ZDV VWDUWHG IURP WKH FRPPRQ PDVWHU SXOVH JHQHUDWRU 03*  ORFDWHG in one of the power supplies. In another power supply instead of 03* WKH 02±3$ FKDQQHO V\QFKURQL]DWLRQ EORFN DQG WKH YROWDJH stabilization of hydrogen thyratrons were used. The synchronization unit is structurally a cylindrical wire (copper) rheostat, to the middle PRELOH WHUPLQDO RI ZKLFK LV FRQQHFWHG WKH RXWSXW IURP 03* DQG WR WKH WHUPLQDO WHUPLQDOV ± WKH JULGV RI WKH WK\UDWURQV 7KH synchronization unit operates as a delay line, which allows shifting WKH FXUUHQW SXOVHV RI WKH 02 DQG 3$ FKDQQHOV UHODWLYH WR HDFK RWKHU ZLWKLQ  QV ,QLWLDOO\ SXOVHG ERRVWLQJ DXWRWUDQVIRUPHUV ZHUH used in the two-channel thyratron power supply with a voltage doubling scheme which were combined together with the magnetic links of the pulse compression into a separate unit. Then, a more convenient circuit with a capacitive voltage doubling was applied. In the latter case, the elements for increasing the voltage and magnetic compression of the current pulses were compactly installed directly in the modulators of the power supplies. A schematic electrical diagram of the two-channel thyratron power supply based on two ,3V ZLWK D GLUHFW FLUFXLW IRU WKH H[HFXWLRQ RI SXPS PRGXODWRUV is shown in Fig. 5.27 a LWV H[WHUQDO DSSHDUDQFH LV VKRZQ LQ )LJ

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5.22. The block for synchronization and stabilization of the glow voltage of the thyratrons is installed in the left power source (in the EORFNZLWKWKHZKLWHSDQHO LQVWHDGRIWKH03*EORFN7KHFRPPRQ master pulse oscillator is located in the right power source, above which there is a block with an autotransformer of voltage doubling DQG D PDJQHWLF OLQN RI WKH LPSXOVH FRPSUHVVLRQ %RWK ,3 SRZHU supplies are connected to the network via a voltage regulator of the 6760 W\SH ZKLFK DOORZV WR LQFUHDVH WKH VWDELOLW\ RI WKH RXWSXW parameters of the laser. 7ZRW\SHVRIDWZRFKDQQHOODPSSRZHUVRXUFH±3OD]DQG,3/ RQWKHEDVLVRIPRGXODWLQJZDWHUFRROHGYDFXXPODPSV*0, $±ZHUHLQYHVWLJDWHG7KHLUDSSHDUDQFHLVVKRZQLQ)LJVDQG 8QGHUWKH.DUHOLDUDGLDWRULQ)LJWKHUHLVWKH,3/± modulator block, on the right under the measuring chamber there LV D FXUUHQW VRXUFH IRU VXSSO\LQJ WKH PRGXODWRUV WR WKH OHIW ± WKH control cabinet of the source. The principal electrical circuits of these

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power supplies are practically the same (Fig. 5.27 b). In systems for stabilizing the power of laser radiation, there are differences. In ,3/SDUWRIWKHODVHUUDGLDWLRQFRQYHUWHGE\WKH7,VHQVRU into an electrical signal is fed to the matching system, and if there is a deviation in the reference signal, a corresponding signal is sent WR WKH FRQWURO JULGV RI WKH *0, $ ODPSV RQ ERWK FKDQQHOV to maintain the specified the level of average radiation power. In WKH 3OD] WKH DYHUDJH FXUUHQW LQ WKH PRGXODWRU RI HDFK FKDQQHO LV PDLQWDLQHGDWDJLYHQOHYHO2XWSXWSDUDPHWHUVRIWKH.DUHOLDUDGLDWRU ZLWKWKHVHODPSVRXUFHVDUHDSSUR[LPDWHO\WKHVDPH7KH3OD]KDVD higher anode voltage and as a result less loss of power on the lamps DQG D ORZHU ZDWHU IORZ :KHQ XVLQJ WKH ODPS SRZHU VRXUFHV WKH power consumption of the AE is higher, and therefore the operating conditions of its cathode and discharge channel are heavier than when using thyratron power supplies. Table 5.5 presents the main results of the Kareliya CVL research ZLWK WZRFKDQQHO WK\UDWURQ SRZHU VRXUFHV EDVHG RQ WZR ,3 DQG ODPS VRXUFHV ,3/± DQG 3OD] 7KH .DUHOLD &9/ RSHUDWHV DFFRUGLQJ WR WKH 02±6)&±3$ VFKHPH The operating modes of power supplies (voltages, currents, VZLWFKHG SRZHUV 35)  DUH RSWLPL]HG EDVHG RQ WKH FRQGLWLRQV RI PD[LPXP UDGLDWLRQ SRZHU :LWK WKH XVH RI WKH ODPS SRZHU VRXUFHV SXPS SXOVHV ZLWK KLJKHU 35) VWHHSHU IURQWV DQG KLJK temporal stability are formed. The latter circumstance is important IRU SURYLGLQJ V\QFKURQRXV RSHUDWLRQ RI WKH 02±3$ V\VWHP 7KH instability of pulse synchronization in the lamp sources does not H[FHHG  QV LQ WKH WK\UDWURQ SXOVHV LW LV  WLPHV KLJKHU As can be seen from this table, when using a thyratron power VXSSO\ EDVHG RQ WZR ,3V ZLWK D GLUHFW HOHFWULFDO FLUFXLW RI WKH PRGXODWRUVWKHDYHUDJHUDGLDWLRQSRZHUDWN+]35)ZDVDERXW :WKHHIILFLHQF\RIWKHUDGLDWRUZDVWKHSUDFWLFDOHIILFLHQF\ IURP WKH UHFWLILHU RI WKH SRZHU VRXUFH   DQG ODVHU HIILFLHQF\ IURP WKH QHWZRUN  :KHQ XVLQJ WKH YROWDJH GRXEOLQJ VFKHPH and magnetic compression of the current pulses, the corresponding YDOXHV DUH  :   DQG  ,Q WKH FDVH RI WKH ODPS power sources, higher energy characteristics are achieved, since the FXUUHQW SXOVHV JHQHUDWHG E\ WKHP KDYH D VKRUWHU GXUDWLRQ a QV  DQG D VWHHSHU IURQW a QV  'XH WR WKH VKRUW GXUDWLRQ RI WKHSXPS SXOVHVWKHSRZHUFRQVXPHGE\WKHUDGLDWRULVKLJKHUDQGLVN: LQWKHFDVHRIWK\UDWURQSRZHUVXSSOLHVDQGN:IRUWKHGLUHFW circuit and for the voltage doubling circuit, respectively).

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Fig. 6.19. The intensity distribution in the plane of the focused radiation beam (in the processing light spot of the ALTI).

the CUCT, a power distribution board and a water cooling system with a temperature feedback sensor. The radiator of the pulsed CVL is an industrial sealed-off laser $( RQ FRSSHU YDSRXU WKH .XORQ PRGHO */, &KDSWHU  7DEOH 4.3), placed in a cylindrical water-cooled heat sink with a tilting top cover. The mirrors of the optical resonator are mounted along the ends of the heat detector. The telescopic UR is used with a gain of M 7KHUDGLXVRIFXUYDWXUHRIWKHEOLQGPLUURULV R blind  mm, output R out  ± PP  DQG  LQ )LJ   7R HOLPLQDWH WKH HIIHFW RI DLUKHDW IOX[HV DW WKH HQGV RI WKH KRW $( DQG FDXVH LQVWDELOLW\RIWKHSRVLWLRQRIWKHD[LVRIWKHEHDPSDWWHUQRIWKHODVHU beam, the space between the mirrors of the resonator and the heat sink is sealed by dielectric tubes. The use of the optical honeycomb table with vibration damping supports, the placement of heat-loaded AE in a cooled heat sink, WKH VHDOLQJ RI WKH +3 ILHOG DQG WKH PDLQWHQDQFH RI D FRQVWDQW WHPSHUDWXUH LQ WKH GHVLJQ RI WKH H[SHULPHQWDO VHWXS KDYH PDGH LW SRVVLEOH WR HOLPLQDWH WKH LQVWDELOLWLHV RI WKH EHDP D[LV RI WKH GLIIUDFWLRQ EHDP DQG WKH SXOVHG HQHUJ\7KHVH PHDVXUHV PD[LPDOO\ improved the quality of microprocessing materials. The SFC collimator is a mirror and is formed by two concave spherical mirrors with a radius of curvature R PPSRVLWLRQV 7 and 8), in the focus of the input mirror of which is located a

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