Inls-Mj — 11221 18Th ECLIM EUROPEAN CONFERENCE on LASER INTERACTION with MATTER

INlS-mJ — 11221 18th ECLIM EUROPEAN CONFERENCE ON LASER INTERACTION WITH MATTER

PRAGUE, MAY4-8, 1987

BOOK OF ABSTRACTS

Organized by Faculty of Nuclear Science and Physical Engineering Technical University of Prague in collaboration with Institute of Physics of Czechoslovak Academy of Sciences 18th ECLIM EUROPEAN CONFERENCE ON LASER INTERACTION WITH MATTER

Sponsored by

Ministry of Education Czechoslovak Academy of Sciences Czechoslovak Atomic Energy Commission

Faculty of Nuclear Science and Physical Engineering Technical University of Prague Brehova 7, 115 19 Praha 1, Czechoslovakia Telex: 121 254 ECLIM18: CONFERENCE SCHEDULE

MONDAY MAY 4

G-l 10.00 - 10.40 Opening Session R-l 11.00 - 12.40 Review Papers 1 1-1 14.00 - 15.30 Invited Papers 1 0-1 16.00 - 17.30 Oral Contributions 1

COCKTAIL

TUESDAY MAY 5

R-2 9.00 - 10.40 Review Papers 2 P-1 11.00 - 12.30 Posters 1 W-l + 11.00 - 12.30 Workshop 1: Research Programs for Small Laser Systems 1-2 14.00 - 15.30 Invited Papers 2 0-2 16.00 - 17.30 Oral Contributions 2 WEDNESDAY MAY 6

R-3 9.00 - 10.40 Review Papers 3 P-2 11.00 - 12.30 Posters 2 0-3 11.00 - 12.30 Oral Contributions 3

+++ AFTERNOON AT LEISURE + H-+

++ + DINNER + H-+ THURSDAY MAY 7 R-4 9.00 - 10.40 Review Papers 4 P-3 11.00 - 12.30 Posters 3 W-2+ 11.00 - 12.30 Workshop 2: Computational Physics of High Energy Densities 1-3 14.00 - 15.30 Invited Papers 3 0-4 16.00 - 17.30 Oral Contributions 4 FRIDAY MAY 8 R-5 9.00 - 10.40 Review Papers 5 R-6 11.00 - 12.40 Review Papers 6: Particle Beams P-4+ 11.00 - 12.30 Posters 4: Postdeadline Papers 1-4 14.00 - 15.30 Invited Papers 4 G-2+ 16.00 - 16.40 Closing Session +Abstracts not available

Review papers Invited papers Oral contributions 25 min 15 min 15 min

- 3 - ECLIM18: ABSTRACTS (AS RECEIVED BY MARCH 1, 1987)

MONDAY MAY 4

G-l+ OPENING SESSION 10.00 - 10.40 Chairman: G. Loncar Fac. Nucl. Sci., Tech. Univ. of Prague Co-chairman: I. Stoll, Dean Fac. Nucl. Sci.,, Tech. Univ. of Prague

Opening of the Conference G-l-1 Introductory Talk N.G. BASOV Lebedev Institute, Acad. Sci. USSR

R-l REVIEW PAPERS 1 11.00 - 12.40 Chairman: A.A. Offenberger University of Alberta

R-l-1 Laser Plasma Research at Garching S. WITKOWSKI MPQ, Garching 037 R-l-2 Recent Results in Laser Produced Plasma Studies at the SERC Central Laser Facility M. H. KEY RAL 038 R-l-3 Laser Fusion Research in the USSR N.G. BASOV, E.G. GAMALY, V.B. ROZANOV, G.V. SKLIZKOV Lebedev Institute, Acad. Sci. USSR -039 R-l-4 Ultra-High Pressure, Direct-Drive, Ablative Compression Experiments R.L. McCRORY LLE, University of Rochester 040

- 5 - 1-1 INVITED PAPERS 1 14.00 - 15.30 Chairman: R.L. McCrory LLE, University of Rochester

1-1-1 Particle Simulation of Nonlinear Resonance Absorption S. HULLER, P. MULSER Technische Hochschule Darmstadt 041 1-1-2 Hot Electron Generation in Laser-Produced Plasma V.B. ROZANOV, S.A. SHUMSKY Lebedev Institute, Acad. Sci. USSR -04? 1-1-3 Invited Paper G. VELARDE ETS Ingenieros Industriales, Univ. Politec. de Madrid 043 1-1-4 On the Energy Cumulation Limits Under Laser Compression of Matter E.G. GAMALY Lebedev Institute, Acad. Sci. USSR -044 I-l-f) Volume Ignition of Laser Driven Fusion Pellets and Double Layer Effects H. HORA, L. CICCHITELLI, M.P. GOLDSWORTHY, R.S. RAY, R.J. STENING, H. SZICHMAN University of New South Wales 045 1-1-6 Muonic Superdense Matter T. TAJIMA The University of Texas at Austin 046

- 6 - 0-1 ORAL CONTRIBUTIONS 1 16.00 - 17.30 Chairman: G. Velarde ETS Ingenieros Industriales Univ. Politec. de Madrid

0-1-1 Anomalies in the Stimulated Raman Spectrum from Laser-Produced Plasmas T.J.M. BOYD, G.A. GARDNER, G.A. COUTTS University of Wales 047 0-1-2 Propagation and Detuning Effects in Plasma Beat-Wave Generation S.J. KARTTUNEN Technical Research Centre of Finland R.R.E. SALOMAA Helsinki University of Technology 048 0-1-3 Electrons Acceleration Under Resonance Interaction of Laser Beam with Inhomogeneous Plasma N.S. EROKHIN, S.S. MOISEEV, R.Z. SAGDEEV Institute for Space Research, Moscow 049 0-1-4 Flux Conduction Effect on Laser-Induced Density Profile and Plasma Ablation Near Plasma Resonance Layer D.P. SINGH, M. VASELLI Instituto di Fisica Atomica e Molecolare, Pisa R. SINGH Indian Institute of Technology 050 0-1-5 Two-Dimensional Langrangean Modelling of Planar Targets J. VIRMONT, B. FARAL Ecole Polytechnique, Palaiseau 051 0-1-6 Uniformity of Illumination in Direct-Drive Laser Fusion W. SEKA, T.J. KESSLER, S. SKUPSKY, F.J. MARSHALL, P.A. JAANIMAGI, M.C. RICHARDSON, J.M. SOURES, C.P. VERDON, R. BAHR LLE, University of Rochester 052

- 7 - TUESDAY MAY 5

R-2 REVIEW PAPERS 2 9.00 - 10-40 Chairman: J.M. Lindl LLNL

R-2-1 Activity Related to Laser i.c.f. at 0.26 urn, and High Intensity Laser Aplications E. FABRE Ecole Polytechnique, Palaiseau 055 R-2-2 Problems in Dense Plasma Diagnostics A.S. SHIKANOV Lebedev Institute, Acad. Sci. USSR -056 R-2-3 Low Preheat Implosion Experiments with Cryogenic Fuel Targets J.T. LARSEN 057 R-2-4 Recent Advances in Laser Fusion C. YAMANAKA ILE, Osaka University -058

P-l POSTERS 1 11.00 - 12.30 Secretary: A. Jancarek Fac. Nucl. Sci., Tech. Univ. of Prague

Laser Plasma Theory 1

P-l-1 Photon Statistics of Nonclassical Radiation in Four-Wave Mixing V. PERINOVA Palacky University, Olomouc 059 P-l-2 Absorption of Energy by Cold Inhomogeneous Plasma from an External Source of Electromagnetics Radiation Z. SEDLACEK Inst. of Plasma Phys., Czech Acad. Sci. B. ROBERTS University of St Andrews 060

- 8 - P-l-3 Total Absorption of Unpolarised Radiation in a Stratified Plasma S. VUKOVIC, R. DRAGILA, A. SMITH Australian National University 061 P-l-4 Stimulated Raman Scattering in the Presence of Filamentation H.C. BARR, T.J.M. BOYD, G.A. COUTTS University of Wales 062 P-l-5 The Raman Instability: Non Local Effects and the Transition Between Absolute and Convective Regimes H.C. BARR, T.J.M. BOYD, G.A. COUTTS University of Wales 063 P-l-6 Role of Langmuir Wave Non-Linearities in Stimulated Raman Scattering G. BONNAUD Centre d Etudes de Limeil, Vi1leneuve-St-Georges D. PESME Centre de Phys. Theor. Ecole Polytechnique, Palaiseau 064 P-l-7 Nonstationary Stimulated Brillouin Scattering in the Strong Coupling Case C. MONTES Laboratoire de Physique de la Matiere Condensee, Nice R. PELLANT Ecole Polytechnique, Palaiseau 065 P-l-8 Benard Instability in Laser-Produced Plasmas D. BASSETT, 0. WILLI Imperial College, London R.G. EVANS RAL 066 P-l-9 Second Harmonic Generation from Underdense Plasma A. GIULIETTI, L. NOCERA Instituto do Fisica Atomica e Molecolare D. GIULIETTI, F. CORNOLTI, M. LUCCHESI Universita di Pisa G.P. BANFI Universita di Pavia CHEN ZEZUN Shangai Institute of Optics and Fine Mechanics 067 P-l-10 Role of Normal Modes in Harmonic Generation L. NOCERA Instituto di Fisica Atomica e Molecolare, Pisa 068

- 9 - f-I-:i Generation of the Higher Harmonics of Powerfu] Laser Radiation in Inhomogerecur Plaprr-i A.G. LITVAK, A.M. FE1GIN, E.A. CHERNOV/ Inst. Applied Physics, Acad. Sci. "SSh •'69

P-l-12 Resonant Excitation of Nonlinear Langxuji Waves, Electron Trapping, and Wave Brt&king A. BERGMANN, H. SCHMABL, P. MULSEB Technische Hochschuie Darmstadt 070

P-l-13 Structure Stability of the Wave Collapses in Media with Local Nonlinear!ty A.G. LJTVAK, E.I. RAKOVA, A.M. SEBGEEV Inst. Applied Physics, Acad. Sci. USSR 07!

P-l-14 Dynamics of the Wave Beams in Media with Relaxation Nonlinearity V.A. MIRONOV, A.M. SERGEEV, A.V. KHIMICH Inst. Applied Physics, Acad. Sci. USSR 072

P-l-15 The Self-Focusing Instability of a Laser Beain in a Nonhomogeneous Plasma at Thermal Nonlinearity N.S. EROKHIN, A.D. FADEEV Inst. Appl. Mathematics, Acad. Sci. USSR 073

P-l-16 Capture and Entrainment of Electromagnetic Wave Packets Into Supercritical Regions of Inhomogeneous Plasma by Ion-Sound Waves E.M. GROMOV, V.I. TALANOV Inst. Applied Physics, Acad. Sci. USSR 074

P-l-17 Electrons Acceleration in Plasma by the Action of Intense Electromagnetic Radiation E.M. GAVRILOV, V.F. SHVETS Scientific Council on Complex Problem "Cybernetics", Acad. Sci. USSR A.M. RUBENCHIK Inst. Aut. and Elect., Acad. Sci. USSR 075

Hydrodynamics and Radiation

P-l-18 Flux-Relaxed Thermal Conduction and its Application to Electron Heat Transfer E.I. LEVANOV, E.N. SOTSKY -Inst. Appl. Mathematics, Acad. Sci. USSR 076

P-l-19 The Effect of Space-Variable Heat Conductivity Coefficient on the Laser Corona Basic Parameters E.G. GAMALY, A.E. KISELEV Lebedev Institute, Acad. Sci. USSR 077

- 10 - r.T:l ;:vvri!..':vi; A-; rr./.u:: ; ' •• : , I:,:'. ;-. litec. ;>- y.ac: :a '• 76

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:•;. KALA;., ,. :vr: *.; Kat . Kii- 1. Sc i . . •JY-r:.';. :Jriiv. •• Ir^ri^- ' ?°

Thcoreli f"-.J 1 nvi1 .t"*; g it i 01. ••:: :..-.•'• ! • - •:. F l iamt-nt;a r i; r. ii"; i'.dSHia •(*» r^i >-. J. MKPOUCH, '.;. I .CMC Aft i-ac. If.jcl. 5'"i., T'.--hn. Un.Y. M FiMfi.c I.G. LEBO, Y.B. HOZAWCV Lt'bedev Ins' : t ,i'e. Atari, f.-.i. ''S.'.r c; •.

iiyJrodynami cr and Racist I <3. Fiij'^irs of Laser-T rr.-i Ji a* ec Planar Targets L. DRSKA, J . LTJ-'POUCH. J. VOIJDPA3EK

'.'•- , - •'•' impute? AI ren ra •i.' :•• i • ~ VT I r ; ,•- Thysics of -)i z\>-l •-. '••-.r^ • <>- '• : ... .- L. DRSKA, L. : TSK.A Fac . ;.:u-'- ] . .•:., •-. •:. "'. ] v. • • jr.. ,• .-.-

?'-l-.:S X-Ray Character.?': - -f !,-::••; -?r-7..-. .. Plasma A.V. VTNOGHADOV. V.:<. Sr3I,VAr'j .'-: V Lebedev Inst.ti;'e, Acr:d. Hri. ':-;Sr 83

I-'-1- :-. The Radiation frorr, ;.a?er Fl^ns Plan": Layer Yu.V. AFANASIEV, K.A. KHAC'-IYAIJ Lebedev Institute, Ac "id. fcl. "f-SR 084

P-i-?V Ionization Equi 1 ibriurr. Tor Hiph-Z Laser Produced Plasma J. FARNY, E. WORYIJA IPPLM, Warsaw 0&

P-l-28 Nonequi librium Emission from t3"ie Laser Target Plasma B.W. BAZYLEV, F.T-J. BOROVIK, G.A. VERGU1I0VA, S.I. KASKOVA, V y-. ROZANOV, G.S. ROMAPJOV, L.K. STANCHITS, K.L. STEPANOV. A.V. TETEREY Lebedev Institute, Acad. Sci. USSR 086 P-I-29 Line- Baiiiat Tion Transfer 3n Nvn-Kqui 2 ibriuir Laser Plasma S.I. K.ASKOVA, G.5. ROMANOV, K.L. STrTPAJ/A' Res. Imst. Appl. Phys. Problems, M:r,sk r>8'7 P-1-3O X-Ray Emission from Laser-Heated Spherical Plasmas D. MOSTACCI, R. MORSE University of Arizona J.P. DINGUIRARP Unlversite P. Sabatier, Toulouse 088 P-l-31 Numerical Simulation of the X-Ray Energetics in Spherical Plasma J.P. 0INGUIRARO, D. MOSTACCI, J. BRJAND. A. GOMES, J.C. KIEFFER, Y. QUEMENER. C. ARMAS, L. BEBGE, M. ARMENGAUlJ Universite P. Sabatier, Toulouse P-l-32 Model Calculations of XUV Gain in Lithium-Like Ions from Recombining Laser-Produced Aluminium Plasmas A. KLISNICK, H. GJJEOTJOU, A. SUREAU LSAI, Orsay J. VIRMONT PMI, Palaiseau 090 P-l-33 Electronics Structure of Matter at High Compression: Transition to Fermi-Gas Behaviour J. MEYER-TER-VEHN, W. ZITTEL MPQ, Garching 091 P-l-34 Planck and Rosseland Mean Opacities of High-2 Plasmas G.D. TSAKIRIS, K. EIDNANN MPQ, Garching 092 P-l-35 Radiation Heat Wave Penetration on Cold Matter R. RAMIS ETS Ingenieros Aeronauticos, Univ. Polltec. de Madrid 093 P-l-36 Crystal X-Ray Accelerator T. TAJ IMA The University of Texas at Austin M. CAVENAGO Scuola Normale Superiore, Pisa 094

- 12 - P-l-37 The Alteration of Charged Particle Energy in Plasma Under the Action of a Strong External Electromagnetic Field E.A. ACOPIAN, G.G. MATEVOSSIAN Inst. of Radiophysics and Electronics, Acad. Sci. Armenian SSR 095 P-l-38 Slowing Down of Ions by Ideal Plasma with Arbitrary Degeneracy D.V. ILIN, A.A. LEVKOVSKY, V.E. SHERMAN, O.B. VYGOVSKY Zavod-VTUZ, Leningrad 096 P-l-39 Theory of the Peaked Regimes in Compressed Media N.V. ZMITRENKO, S.P. KURDYUMOV, A.P. MIKHAILOV Inst. Appl. Mathematics, Acad. Sci. USSR 097 P-l-40 New Synergetic Properties of Diffusion Processes in Plasma G.G. ELENIN, E.S. KURKINA Moscow State University N.V. ZMITRENKO, S.P. KURDYUMOV, A.P. MIKHAILOV, A.B. POTAPOV, A.A. SAMARSKII Inst. Appl. Mathematics, Acad. Sci. USSR 098

W-l+ WORKSHOP 1: 11.00 - 12.30 RESEARCH PROGRAMS FOR SMALL LASER SYSTEMS Chairman: A. Ng University of British Columbia Secretary: L. Pina Fac. Nucl. Sci., Tech. Univ. of Prague

1-2 INVITED PAPERS 2 14.00 - 15.30 Chairman: A.S. Shikanov Lebedev Institute, Acad. Sci. USSR

1-2-1 Invited Paper A. CARUSO Energy Research Center, ENEA, Frascati -099 1-2-2 Recent Results of Investigations of the Laser Interaction with Matter at the IPPLM S. DENUS IPPLM, Warsaw 100

- 13 - 1-2-3 Pulsation of Fundamental and Second Harmonic Emission from Nd-Laser Produced Plasma R. DRAGILA, B. LUTHER-DAVIES, A. MADDEVER Australian National University 101 1-2-4 Gain and Radiation Trapping for Long-Laser-Pulse Produced Plasma W. BRUNNER, Th. SCHLEGEL Zentralinstitut fuer Optik und Spektroskopie, Berlin 102 1-2-5 Experimental Studies on Laser Irradiated Thin Foil Targets H.C. PANT Bhabha Atomic Research Centre, Bombay -103 1-2-6 Radiation Transport in Laser-Target Interactions A. NG University of British Columbia -104

0-2 ORAL CONTRIBUTIONS 2 16.00 - 17.30 Chairman: E. Fabre Ecole Polytechnique, Palaiseau

0-2-1 Simulation of Laser-Plasma Interactions with Atomic and Radiation Effects R. MARCHAND, C.E. CAPJACK, R. FEDOSEJEVS University of Alberta Y.T. LEE LLNL 105 0-2-2 Energy Transport Through Thin Aluminium Foil in Laser-Target Experiment R. ARENDZIKOWSKI, S. DENUS, J. FARNY, H. FIEDOROWICZ, K. JEZIAK, W. MROZ, S. NAGRABA, W. PAWLOWICZ, A. WILCZYNSKI, J. WOLOWSKI IPPLM, Warsaw P. BITZAN, L. DRSKA, J. LIMPOUCH, G. LONCAR, L. PINA, J. VONDRASEK Fac. Nucl. Sci., Tech. Univ. of Prague 106

- 14 - 0-2-3 Stimulated Raman Scattering in Long Scalelength Pre-Formed Plasmas A. GIULIETTI Instituto di Fisica Atomica e Molecolare, Pisa 0. WILLI, D. BASSETT, N. ISLAVA Imperial College, London J.S. KARTTUNEN Technical Research Center of Finland 107 0-2-4 Experimental Study of the Filamentation Instability in Short Wavelenght Laser Produced Plasmas C. ARNAS, J. BRIAND, J.C. KIEFFER, A. GOMES, J.P. DINGUIRARD, Y. QUEMENER, L. BERGE, M. ARMENGAUD Universite P. Sabatier, Toulouse 108 0-2-5 Study of Li-Like Ions in Laser-Produced Plasmas for X-UV Laser Research H. GUENNOU, A. SUREAU, C. MOLLER Universite Paris-Sud, Orsay 109 0-2-6 Laser-Driven Implosion Studies Using the Soft X-Ray Emission Measurements * S. DENUS, H. FIEDOROWICZ, K. JEZIAK, P. PARYD, W. PAWLOWICZ, J. WOLOWSKI IPPLM, Warsaw 110

- 15 - WEDNESDAY MAY 6

R-3 REVIEW PAPERS 3 9.00 - 10.40 Chairman: N.G. Basov Leb.edev Institute, Acad. Sci. USSR

R-3-1 Laser-Plasma Experiments at the NOVA Laser Facility E.M. CAMPBELL LLNL 113 R-3-2 Laser-Plasma-Interaction Experiments Using Multikilojoule Lasers R.P. DRAKE LLNL 114 R-3-3 Review Paper J.D. LINDL LLNL 115 R-3-4 o Physical Properties of Super-Dense Plasma and Numerical Modeling of Pulsed Processes at High Energy Concentrations V.E. FORTOV Inst. of Chemical Physics, Acad. Sci. USSR -116

P-2 POSTERS 2 11.00 - 12.30 Secretary: M. Vrbova Fac. Nucl. Sci., Tech. Univ. of Prague

Laser Plasma Theory 2

P-2-1 Resonance Absorption with Self-Consistent Profile Modification E. AHEDO, J.R. SANMARTIN ETS Ingenieros Aeronauticos, Univ. Politec. de Madrid 117

- 16 - P-2-2 Modulation Instability in the Beat Wave Experiment E. PESME, G. LAVAL, N. SYLVESTRE Centre Phys. Theor., Ecole Polytechnique, Palaiseau S. KARTTUNEN Technical Research Centre of Finland R. SALOMAA Helsinki University of Technology 118 P-2-3 Simple Models of Hot Electron Generation in Laser Plasma V.B. ROZANOV, S.A. SHUMSKY Lebedev Institute, Acad. Sci. USSR 119 P-2-4 Dynamical Structure Factor of a Plasma in Terms of Transport Coefficients I. DEHA Univ. de Sciences et de la Technologie, Alger 120 P-2-5 Relaxation of Quantum Systems in Strong Electromagnetic Field - New Nonlinear Effects E.G. PESTOV Lebedev Institute, Acad. Sci. USSR 121 P-2-6 Non-Uniform Irradiation of Spherical Laser Targets J. SANZ, J.R. SANMARTIN, J.A. NICOLAS ETS Ingenieros Aeronauticos Univ. Politec. de Madrid 122 P-2-7 Shock Explosion and Implosion, Analytical Solutions, Approximations Involved A.A. MISHKIN Polytechnic Institute of New York C. ALEJALDRE Junta de Energia Nuclear, Madrid 123

Experimental Studies

P-2-8 Filamentation and Stimulated Brillouin Scattering in Long Scalelenght Pre-Formed Plasma A. GIULIETTI Instituto di Fisica Atomica e Moleculare Pisa, 0. WILLI, D. BASSETT, N. ISLAVA Imperial College, London J.S. KARTTUNEN Technical Research Center of Finland 124

- 17 - P-2-9 Experimental Evidence of Strong Langmuir Turbulence from Second Harmonic Spectra in 1 um Laser produced Plasma J. BRIAND, A. GOMES, J.C. KIEFFER, L. BERGE, C. ARNAS, Y. QUEMENER, J.P. DINGUIRARD, M. ARMENGAUD Universite P. Sabatier, Toulouse D. PESME Centre Phys. Theor., Ecole Polytechnique, Palaiseau 125

P-2-10 Hydrodynamic Instability of Contact Area of Two Different Density Accelerated Flows A.N. ALESHIN, E.G. GAMALY, S.G. ZAITSEV, E.V. LAZAREVA, I.G. LEBO, V.B. ROZANOV, S.N. TITOV, E.I. CHEBOTAREVA Krzhizhanovsky Power Institute Lebedev Institute, Acad. Sci. USSR 126

P-2-11 Recording of Surface Motion by Doppler Laser Interferometry M.M. ABAZEKHOV, M.I. BELOVOLOV, V.I. VOVCHENKO, T.B. VOLYAK, I.K. KRASYUK, A.V. KUZNETSOV, P.P. PASHININ, A.M. PROKHOROV, A.Yu. SEMENOV, V.E. FORTOV Institute of General Physics, Acad. Sci. USSR , 127 P-2-12 Measurement of Thin Foil Movement Velocities Inside a Cylinder Channel V.I. VOVCHENKO, T.B. VOLYAK, I.K. KRASYUK, P.P. PASHININ, A.M. PROKHOROV, A.Yu. SEMENOV Institute of General Physics, Acad. Sci. USSR 128 P-2-13 Thin Foil Deceleration Dynamics in Xenon Atmosphere V.I. VOVCHENKO, I.K. KRASYUK, A.L. NEE, P.P. PASHININ, A.M. PROKHOROV, A.Yu. SEMENOV, V.E. FORTOV Institute of General Physics, Acad. Sci. USSR 129 P-2-14 Spontaneous Electric Potentials Occurring at Laser Acceleration of Thin Foils in Cylindrical Channel V.I. VOVCHENKO, P. HEIL, I.K. KRASYUK, P.P. PASHININ, A.M. PROKHOROV, A.Yu. SEMENOV Institute of General Physics, Acad. Sci. USSR 130

- 18 - P-2-15 Current Generation in Laser Plasma Using the Preaction of Low Radiation Pulse on the Target E.M. BARKHUDAROV, G.V. GELASHVILI, G.G. GUMBERIDZE, M.I. TAKTAKISHVILL Inst. Phys., Tbilisi, Acad. Sci. USSR 131 P-2-16 Registration of Spontaneous Magnetic Fields in Laser Produced Plasma on the "DELFIN-1" Installation N.G. BASOV, E.G. GAMALY, A.A. RUPASOV, G.S. SARKISOV Lebedev Institute, Acad. Sci. USSR S. DENUS, T. PISARCHIK, J. WOLOWSKI IPPLM, Warsaw 132 P-2-17 Interaction of the Short Pulse COp Laser Radiation with High-Z Targets J. BADZIAK, S. DENUS. D. DZWIGALSKI, J. FARNY, J. KOSTECKI. M. MACZUR, P. PARYS, J. WOLOWSKI, R. JAROCKI, K. JANULEWICZ, Z. SIKORSKI IPPLM, Warsaw 133 P-2-18 New Aspherical Targets for Investigation of Laser Plasma Compression W. MUNIAK, R. SUCHANSKA IPPLM, Warsaw 134 P-2-19 Colliding Foil Experiments with Strong Bidimensional Effects B. FARAL, R. FABBRO Ecole Polytechnique, Palaiseau F. COTTET, J.P. RAMAIN ENSMA, Poitiers 135 P-2-20 Shock Coalescence Using Shaped Lasers Pulses D. RILEY, D. BASSETT, S. COE, M. GIVON, 0. WILLI Imperial College M. GRANDE, S.J. ROSE, P.T. RUMSBY RAL 136 P-2-21 2D Study of the Laser Shock Wave Breakout at the Rear Face of a Metallic Target F. COTTET, L. MARTY, M. HALLOUIN, J.P. ROMAIN Laboratoire d Energetique et Detonique, Poitiers J. VIRMONT, R. FABBRO, B. FARAL Ecole Polytechnique, Palaiseau 137

- 19 - P-2-22 X-Ray Absorption Spectroscopy of Laser Produced Plasmas C.L.S. LEWIS, R.E. CORBETT, E. ROBERTSON, S. SAADAT. D. O*NEILL Queens University, Belfast J.D. KILKENNY, R.W. LEE LLNL 138 P-2-23 Spatially Sensitive Spectroscopic X-Ray Diagnostics for Line Focus Experiments M. GRANDE, T. TOMIE, E. FILL RAL 139 P-2-24 Diagnostics of Gold Laser Plasmas J.C. GAUTHIER, J.P. GEINDRE, P. MONIER, C. CHENAIS-POPOVICS, N. TRAGIN Universite Paris-Sud, Orsay, and Ecole Polytechnique, Palaiseau 140 P-2-25 Comparative X-ray Spectroscopy of Various-Z Elements with Absolute Wavelength Calibration J.E. BALMER, W. LAMPART, K. WEBEk University of Berne 141 P-2-26 Laser Shell Target Images in X-Ray Spectral Line Self-Radiation K. GOETZ, G. KORN, M.P. KALASHNIKOV, A.M. MAKSICHUK, Yu.A. MIKHAILOV, A.V. RODE, G.V. SKLIZKOV, A.G. TIKHONOV, S.I. FEDOTOV, E. FORSTER Lebedev Institute, Acad. Sci. USSR 142 P-2-27 Experimental Investigation of Laser Thermonuclear Target Preheating N.G. BASOV, S.Yu. GUSKOV, M.P. KALASHNIKOV, Yu.A. MIKHAILOV, V.B. ROZANOV, A.V. RODE, A.V. SARTORY, G.V. SLIZKOV, S.I. FEDOTOV Lebedev Institute, Acad. Sci. USSR 143

P-2-28 Suppression of Recombination in Expanding Laser-Produced Plasma S.V. BOBASHEV, P.M. SHIMANOVSKY, L.A. SHMAENOK Physical-Technical Institute, Acad. Sci. USSR 144

Laser Systems 1

P-2-29 Investigation of the Radiation Propagation in the Channel of the High Power Laser A. DUBIK, A. SARZYNSKI IPPLM, Warsaw 145

- 20 - P-2-30 Investigations of Efficiency of Nd Glass Laser Amplifiers A. DUBIK, J. GODZIK, J. MAKOWSKI, J. OWSIK IPPLM, Warsaw 146 P-2-31 Active Pulse Shaping in Subnanosecond Range for High Power Nd Glass Laser System S. DENUS, A. DUBIK, J. MARCZAK, J. OWSIK, J. PIOTROWSKI IPPLM, Warsaw G.V. SKLIZKOV, J.V. SENATSKIJ, B.J. IWANOW, N.E. BYKOWSKIJ Lebedev Institute, Acad. Sci. USSR 147 P-2-32 Liquid Crystal Isolators for High Power Laser Systems T. CESARZ, A. DUBIK, J. OWSIK IPPLM, Warsaw J. KUSNIERZ, A. SZYMANSKI Technical Univ. of Rzeszow 148

0-3 ORAL CONTRIBUTIONS 3 11.00 - 12.30 Chairman: W. Brunner Zentralinstitut fuer Optik und Spektroskopie, Berlin

0-3-1 Space and Time Resolved Measurements of Ablation Uniformity A.J. COLE, M.H. KEY RAL D. BROWN, P. NORREYS, E. WOODING Royal Holloway Bedford New College 149 0-3-2 Observation of Ion Correlation in Shock Compressed Laser Produced Plasma T.A. HALL, A. DJAOUI, R.W. EASON, C.L. JACKSON, B. SHIWAI University of Essex S.L. ROSE, A. COLE, P. APTE 150 RAL 0-3-3 Laser Acceleration of Thin Foils in Conic Targets V.I. VOVCHENKO, T.B. VOLYAK, Yu.S. KASYANOV, I.K. KRASYUK, P.P. PASHININ, A.M. PROKHOROV, A.Yu. SEMENOV Institute of General Physics, Acad. Sci. USSR L. PINA Fac. Nucl. Sci., Tech. Univ. of Prague 151

- 21 - 0-3-4 Magnetic Field Behavior Beyond the Laser Spot S.R. GOLDMAN, R.F. SCHMALZ MPQ, Garching 15? 0-3-5 Measurements of Self Generated Magnetic Fields in 0.25 um Laser Produced Plasmas Using the Zeeman Effect J. BRIAND, J.C. KIEFFER, A. GOMES, C. ARNAS, J.P. DINGUIRARD, Y. QUEMENER, L. BERGE, M. ARMENGAUD Universite P. Sabatier, Toulouse 153 0-3-6 X-Ray Emission and Radiation Transport in Laser-Produced Plasma K. EIDMANN, R. SCHMALZ, G.D. TSAKIRIS MPQ, Garching 154

- 22 - THURSDAY MAY 7

R-4 REVIEW PAPERS 4 9.00 - 10.40 Chairman: J. Olsen Pulsed Power Sciences 1200, Sandia National Laboratories

R-4-1 KrF Laser/Plasma Interaction Studies at the University of Alberta A.A. OFFENBERGER, R. FEDOSEJEVS, R. POPIL, J. SANTIAGO, Y.Y. TSUI University of Alberta P.D. GUPTA Bhabha Atomic Research Centre, Bombay 157 R-4-2 KrF Laser-Plasma X-Ray Sources - Generation and Applications F.O'NEILL RAL 158 R-4-3 Krypton Fluoride Laser Drivers for Achieving Very High Energy Densities R.J. JENSEN LANL -159 R-4-4 Laser-Matter Interaction Studies Using a Multi-Kilojoule KrF Laser at Los Alamos National Laboratory L.S. BLAIR, D.C. CARTWRIGHT, S.V. COGGESHALL, L. FOREMAN, P.D. GOLDSTONE, J.A. HANLON, A. HAUER, R. KRISTAL, J. McLEOD, W.C. MEAD, L.A. ROSOCHA, Y. YOUNG LANL L.M. MONTIERTH University of Arizona 160

- 23 - P-3 POSTERS 3 11.OO - 12.30 Secretary: K. Rohlena Inst. of Physics. Czech. Acad. Sci.

Laser Systems 2

P-3-1 Condensed- and Compressed-Gas Lasers N.G. BASOV, V.A. DANILYCHEV Lebedev Institute, Acad. Sci. USSR 161 P-3-2 Advantages of a Multipass Amplifier I.V. EPATKO, P.P. PASHININ, R.V. SEROV Institute of General Physics, Acad. Sci. USSR 162 P-3-3 Iodine Laser Driver PERUN V. HERMOCH, M. CHVOJKA, B. KRALIKOVA, J. KRASA, L. LASKA, K. MASEK, J. MUSIL, S. POLAK, K. ROHLENA, J. SKALA, J. SCHMIEDBERGER Inst. of Physics, Czech. Acad. Sci. 163 P-3-4 Investigations of Pulsed Laser Near-Surface Plasma Formations L.Ya. MINKO, A.N. CHUMAKOV Institute of Physics, BSSR Acad. Sci., Minsk 164 P-3-5 The Effect of Targets Initial State on the Process of Laser Induced Plasma Formation M.R. BEDILOV, H.B. BEYSENBAEVA, M.C. SABITOV, P.K. KHABIBULLAEV, S.A. KARAMISHEVA, R. ABDUPATAEV Institute for Nuclear Physics, Tashkent 165 P-3-6 Secondary Optical Break-Down on Laser Plasma Boundaries in the Air and Plasma Mirror Formation Under Microsecond Laser Pulse A.M. PROKHOROV, V.A. SPIRIDONOV, V.B. FEDOROV, I.V. FOMENKOV Institute of General Physics, Acad. Sci. USSR 166

- 24 - P-3-7 Low-Threshold Mandelstam-Brillouin Stimulated Scattering on Neodymium Laser Plasma Mirror and Spectral Characteristics of Ultrashort Pulse Generation A.M. PROKHOROV, V.B. FEDOROV, I.V. FOMENKOV Institute of General Physics, Acad. Sci. USSR 167 P-3-8 Ultrashort Pulse Initiation in Neodymium Laser with Plasma Mirror Using an Auxiliary Nanosecond Laser A.M. PROKHOROV, V.B. FEDOROV, I.V. FOMENKOV Institute of General Physics, Acad. Sci. USSR 168 P-3-9 GSGG:Cr3+, Nd3+ - Laser with SBS-Mirror and Plasma Shutter S.Yu. NATAROV, P.P. PASHININ, E.I. SHKLOVSKY Institute of General Physics, Acad. Sci. USSR 169

Diagnostic Methods

P-3-10 Multiframe High-Speed System for Interferometric Plasma Photography in Laser Fusion Experiments A.D. VALUEV, B.L. VASIN, R.G. MAY, A.I. SMELKOV, G.V. SKLIZKOV, S.I. FEDOTOV Lebedev Institute, Acad. Sci. USSR 170 P-3-11 The System of Schlieren-Photography for Shock-Wave Registration at the "DELFIN-1" Laser Facility A.D. VALUEV, B.L. VASIN, V.M. ZUBKOV, M.YU. MAZUR, YU.A. MIKHAILOV, G.V. SKLIZKOV, S.I. FEDOTOV, S.A. CHAUSHANSKY Lebedev Institute Acad. Sci. USSR 171 P-3-12 Developments and Applications of the Refractive Fringe Diagnostics P.F. CUNNINGHAM, M.M. MICHAELIS, R.N. CAMPBELL, J. WALTHAM, M. NOTCUTT University of Natal 172 P-3-13 Holographic Diagnostics of Plasma Density Distribution Using Abel Inversion CHEN ZEZUN, A. GIULIETTI, L. NOCERA, D. GIULIETTI, M. LUCCHESI Instituto di Fisica Atomica e Molecolare, Pisa 173

- 25 - P-3-14 Deconvolution of Electron Density Profiles with Sharp Gradients from Laser Plasma Interferograms S.F. GONCHAROV, R.V. SEROV, V.P. YANQVSKY Institute of General Physics, Acad. Sci. USSR 174 P-3-15 On the Possibility to Observe Spontaneous Magnetic Fields in Compressed Laser Target S.S. KOTELNIKOV Polytechnical Institute, Leningrad I.G. LEBO, V.B. ROZANOV Lebedev Institute, Acad. Sci. USSR 175 P-3-16 The Calibration of Silicon PIN Detectors for X-Ray Plasma Diagnostics L. PINA Fac. Nucl. Sci., Tech. Univ. of Prague E. KROUSKY, 0. RENNER Inst. of Physics, Czech. Acad. Sci. I. BENC, J. URBANEC Tesla Vacuum Technique, Prague 176 P-3-17 X-ray Image-Converter Camera "Almaz-R" Based on an Image Converter Tube with Demountable Photocathodes V.K. CHEVOKIN, B.E. DASHEVSKY, V.A. PODVYAZNIKOV, A.M. PROKHOROV, A.V. PROKHINDEEV Institute of General Physics, Acad. Sci. USSR 177 P-3-18 Modulation Transfer and Resolution in X-ray Pinhole Photography of Laser-Produced Plasmas J. MIKA, J.E. BALMER University of Berne 178 P-3-19 Design Aspects of a 2-D X-Ray Spectrometer C.L.S. LEWIS Queens University, Belfast B.S. FRAENKEL Racah Institute, Jerusalem P.F. CUNNINGHAM University of Natal 179 P-3-20 Galvanoplastic Replica Mirrors for Laser Plasma Soft X-Ray Imaging H. FIEDOROWICZ, S. NAGRABA IPPLM, Warsaw P. HUDEC, B. VALNICEK Astronomical Inst., Czech. Acad. Sci. 180 P-3-21 Particle Diagnostics of Laser Produced Plasma B.YU. SHARKOV Inst. Theor. Exper. Phys., Moscow 181

- 26 - P-3-22 Application of the CR-39 Tracks Detector to Registration of Low Energy Charge Particles J. FARNY, E. WORYNA IPPLM, Warsaw YU.A. ZAKHARENKOV, A.A. EROKHIN Lebedev Institute, USSR Acad. Sci. 182 P-3-23 Laser Fusion Plasma Diagnostics from the Secondary Fusion Reaction Products N.G. BASOV, S.Yu. GUSKOV, D.V. ILIN, A.A. LEVKOVSKY, V.B. ROZANOV, V.E. SHERMAN, O.B. VYGOVSKY Lebedev Institute, Acad. Sci. USSR 183 P-3-24 Possible Diagnostics of Plasma of High-Aspect-Ratio Targets in the Laser Fusion by Characteristics of Nuclear Particles O.B. VYGOVSKY, S.Yu. GUSKOV, N.V. ZMITRENKO, D.V. ILIN, V.Ya. KARPOV, A.A. LEVKOVSKY, T.V. MISHCHENKO, V.B. ROZANOV, V.E. SHERMAN Lebedev Institute, Acad. Sci. USSR 184 P-3-25 On a New Method of Analysis Charged Particles Beams Dynamics M.Yu. ROMANOVSKY Institute of General Physics, Acad. Sci. USSR 185

Applications

P-3-26 Three-Layered Target Acceleration in Heavy Ion Fusion Yu.V. AFANASIEV, V.A. ISAKOV, K.A. KHACHIYAN Lebedev Institute, Acad. Sci. USSR 186 P-3-27 Hydrodynamic Effects in Conic Thermonuclear Targets A.V. BUSHMAN, I.K. KRASYUK, B.P. KRYUKOV, P.P. PASHININ, A.M. PROKHOROV, V.F. MININ, A.Yu. SEMENOV, V.E. FORTOV Institute of General Physics, Acad. Sci. USSR 187 P-3-28 Thermonuclear Yield of Targets for Powerful Shortwave Lasers N.G. BASOV, S.Yu. GUSKOV, N.N. DEMCHENKO, V.B. ROZANOV Lebedev Institute, Acad. Sci. USSR G.V. DANILOVA, N.V. ZMITRENKO, V.Ya. KARPOV, T.V. MISHCHENKO, A.A. SAMARSKII Keldysh Inst. of Appl. Math., Acad. Sci. USSR 188

- 27 - P-3-29 On Parameters of Focusing Optics of a Laser Fusion Reactor N.G. BASOV, N.I. BELOUSOV, G.A. VERGUNOVA, P.A. GRISHUNIN, A.E. DANILOV, I.G. LEBO, V.B. ROZANOV, G.V. SKLIZKOV, V.I. SUBBOTIN, S.I. FEDOTOV, V.V. KHARITONOV Lebedev Institute, Acad. Sci. USSR 189 P-3-30 Thermal Calculations for Laser Mirrors V.V. KHARITONOV Moscow Engineering Physics Institute 190 P-3-31 The Cryogenic Targets Heat Stability Under Laser Experiments E.R. KORESHEVA, A.I. NIKKITENKO Lebedev Institute, Acad. Sci. USSR 191 P-3-32 Characteristics of Lithium Film Protection ICF Reactor First Wall S.A. BERENDEEV, D.N. KAGAN, E.E. SHPILRAIN Inst. for High Temperatures, Acad. Sci. USSR I.G. LEBO, V.B. ROZANOV, G.V. SKLIZKOV Lebedev Institute, Acad. Sci. USSR 192 P-3-33 Laser-Produced Shock Waves in Liquids: Applications in Ophthalmology L. DRSKA, K. HAMAL, H. JELINKOVA, J. TUREK, P. VALACH Fac. Nucl. Sci., Tech. Univ. of Prague 193 P-3-34 ArF Laser Ablation on PMMA and Aluminium A. JANCAREK, P. REJFIR, M. VRBOVA Fac. Nucl. Sci., Tech. Univ. of Prague 194

P-3-35 Material Expulsion by TEA C0? Laser P. GAVRILOV, V. KRAJICEK, M. VRBOVA Fac. Nucl. Sci., Tech. Univ. of Prague 195 P-3-36 Some Physical and Metallurgical Aspects of Formation of Surface Layers on Metal Substrate by Laser Radiation J. ADAMKA, M. BE.LKO, J. STYK Slovak Technical University 196 P-3-37 Craters Produced by Laser Impacts in Solid Targets M. HALLOUIN, F. COTTET, L. MARTY, J.P. ROMAIN Laboratoire d'Energe'tique et Detonique, Poitiers 197 P-3-38 Optimizing the Parameters of Crystal Spectrometers for X-Ray Plasma Diagnostics 0. RENNER Inst. Phys. Czechosl. Acad. Sci. 198

- 28 - P-3-39 Laser Investigation of a Shock Compressed Silicon V.B. MINTSEV, V.E. FORTOV, Y.B. ZAPOROGETS Inst. Chem, Phys., Acad. Sci. USSR 199

W-2+ WORKSHOP 2: 11.00 - 12.30 COMPUTATIONAL PHYSICS OF HIGH ENERGY DENSITIES Chairman: K. Niu Tokyo Institute of Technology Secretary: L. Drska Fac. Nucl. Sci., Tech. Univ. of Prague

1-3 INVITED PAPERS 3 14.00 - 15.30 Chairman: A. Caruso Energy Research Center, ENEA, Frascati

1-3-1 Laser Plasma Research and Applications in CSSR G. LONCAR, L. DRSKA, K. HAMAL, L. PINA, M. VRBOVA Fac. Nucl. Sci., Tech. Univ. of Prague J. MUSIL Inst. of Physics, Czech. Acad. Sci. -201 1-3-2 Mechanism of Conversion of Laser Light into X-Rays R.F. SCHMALZ, K. EIDMANN, J. MEYER-TER-VEHN, R. RAMIS MPQ, Garching 202 1-3-3 Atomic Physics and Spectroscopy in X-Ray Laser Research Modelisation and Experiments J.C. GAUTHIER, J.P. GEINDRE, P. MONIER, C. CHENAIS-POPOVICS Universite Paris-Sud, Orsay 203 1-3-4 Soft X-Ray Amplification in Aluminium Recombining Plasma Produced from Thin Coated Fiber A. CARILLON, P. JAEGLE, G. JAMELOT, A. KLISNICK LSAI, Orsay M. KEY, G. KIEHN, G. PERT, S. RAMSDEN, C. REAGAN, S. ROSE, R. SMITH, T. TOMIE, 0. WILLY RAL 204

- 29 - 1-3-5 Progress in Hydrogenic XUV Recombination Lasers at the RAL C.L.S. LEWIS, R.E. CORBETT, C. REGAN Queens University, Belfast M. GRANDE, M.H. KEY, S.J. ROSE, T. TOMIE RAL G.P. KIEHN, , R. SMITH, 0. WILLI Imperial College, London G.J. PERT, S. RAMSDEN University of Hull 205 1-3-6 Non-Equilibrium Generation of High-Pressure Plasma with a CW C0? Laser Yu.P. RAYZER Institute of Mechanical Problems, Moscow 206

0-4 ORAL CONTRIBUTIONS 4 16.00 - 17.30 Chairman: S. Denus IPPLM, Warsaw

0-4-1 Simultaneous X-Ray and Optical Shadowgraphy of Cavities Heated by A = 0.44 urn Laser Light R. SIGEL, K. EIDMANN, R.F. SCHMALZ, G.D. TSAKIRIS, S. WITKOWSKI MPQ, Garching I.B. FOLDES Central Res. Inst. for Physics, Budapest CHEN SHISHENG Shangai Institute of Optics and Fine Mechanics 207 0-4-2 Comparative Study of X-Ray Generation in a Cavity Heated by 1.3 urn or 0.44 urn Laser Light S. SAKABE ILE, Osaka University R. SIGEL. G.D. TSAKIRIS, P. HERRMANN MPQ, Garching I. FOLDES Central Research Institute of Physics, Budapest 208 0-4-3 The Theory of Active Media in Excimer Lasers A.G. MOLCHANOV Lebedev Institute, Acad. Sci. USSR 209

- 30 - 0-4-4 Ura Coded Aperture Cameras with Spectral or Tomographical Resolution for Laser Imploded Plasma Diagnostics M. YAMANAKA, Y.-W. CHEN, H. MIYAI, N. MIYANAGA, H. NIKI, T. YAMANAKA, Y. IZAWA, C. YAMANAKA ILE, Osaka University S. TAMURA Faculty of Engineering Science, Osaka University 210 0-4-5 Characterisation and Optimisation of a Laser Generated Plasma Source of Soft X-rays for Biological Imaging A.M. ROGOYSKI, C.P. HILLS, A.G. MICHETTE, P. CHARALAMBOUS King's College, London 211 0-4-6 Characterisation and Optimisation of KrF Laser-Plasma X- Ray Source in the 280 eV - 530 eV Photon Energy Range A.M. ROGOYSKI, C.P. HILLS, A.G. MICHETTE King's College, London I.C.E. TURCU, F. O'NEILL, U. ZAMMIT RAL Y. AL-HADITHI, R.W. EASON Essex University 212

- 31 - FRIDAY May 8

R-5 REVIEW PAPERS 5 9.00 - 10.40 Chairman: M.H. Key RAL

R-5-1 Laser Heated Cavities G.D. TSAKIRIS, R. SIGEL, K. EIDMANN, P. HERRMANN, R. PAKULA, S. WITKOWSKI MPQ, Garching I.B. FOLDES Central Res. Inst. for Physics, Budapest S. SAKABE ILE, Osaka University 215 R-5-2 Numerical Simulation of Imploding Thin Shells J.H. GARDNER NRL -216 R-5-3 Extending X-Ray Lasing to Shorter Wavelength D.C. EDER, M.D. ROSEN, R.A. LONDON, S. MAXON LLNL 217

R-6 REVIEW PAPERS 6: PARTICLE BEAMS 11.00 - 12.40 Chairman: S. Witkowski MPQ, Garching

R-6-1 Progress on the Particle Beam Fusion Accelerator II for Light Ion Fusion J.P. VANDEVENDER Pulsed Power Sciences 1200, Sandia National Laboratories 219 R-6-2 Physics of High-Power Light-Ion-Beam-Target Interactions K. YATSUI, Y. SHIMOTORI, Y. ARAKI, K. MASUGATA, S. KAWATA The Technological University of Nagaoka 220 R-6-3 Optimization of Target for ICF and Target Gain K. NIU Tokyo Institute of Technology 221

- 32 - P-4+ POSTERS 4: POSTDEADLINE PAPERS 11.00 - 12.30 Secretary: J. Vondrasek Fac. Nucl. Sci., Tech. Univ. of Prague

1-4 INVITED PAPERS 4 14.00 - 15.30 Chairman: D. Attwood Lawrence Berkeley Laboratory

1-4-1 Spectral Line Profile Measurements on Laser Produced Plasma H.R. GRIEM The University of Maryland -223 1-4-2 Invited Paper B.L. HENKE Lawrence Berkeley Laboratory 224 1-4-3 Some Recent Concepts in ICF Neutron Diagnostics G.H. MILEY University of Illinois at Urbana-Champaign -225 1-4-4 Laser Plasma Application for Laser Development V.B. FEDOROV Institute of General Physics, Acad. Sci. USSR 226 1-4-5 UV Laser Plasma and its Application to Laser Pulse Switching QIHONG LOU Shangai Institute of Optics and Fine Mechanics 227 1-4-6 Vaporization and Recondensation in Laser Driven Reactors: the Limiting Issues and Uncertainties W.J. HOGAN, CH. D. ORTH LLNL 228

- 33 - G-2+ CLOSING SESSION 16.00 - 16.40 Chairman: C. Yamanaka ILE, Osaka University

G-2-1 ECLIM18 Summary: Theory and Computation L. DRSKA Fac. Nucl. Sci., Tech. Univ. of Prague G-2-2 ECLIM18 Summary: Experiments and Applications S. WITKOWSKI MPQ, Garching Closing of the Conference

- 34 - MONDAY

MAY A ECLIM18: R-l-1

Laser plasma research at Garching S. Witkowski Max-Planck-Institut fur Quantenoptik D-8046 Garching, FRG The work is concentrated on basic physics problems relevant to ICF and development of high power lasers. An upgraded iodine laser ASTERIX IV is being reconstructed in a new building. Its 29 cm diameter single beam is designed to deliver an energy up to 2 kJ or a maximum power of 5 TW, the variable pulse duration ranging between 0.1 and 3 ns. A number of new features are introduced that improve the efficiency and the beam quality. Achievement of symmetric current distribution in the flashlamps increases their lifetimes to 3000 shots at full power.

A major part of the work is devoted to the investigation of the soft x-radiation emitted by laser-produced plasma and its interaction with the hydrodynamic. The dependence of soft x-ray spectra emitted from plane targets on the atomic number and intensity and wavelength of the irradiating laser is systematically studied . Experiments with hollow gold spheres as targets demonstrate the radiation heat wave, radiation confinement and approach to black body radiation. Radiation temperatures of up to 200 eV were achieved in joint ILE/MPQ experiments using the GEKKO XII laser in Osaka. Simplified theoretical models allow the order of magnitude determination of opacities and reproduction of essential features of the observed spectra.

Further theoretical and experimental work is being done on some basic physic problems of heavy ion fusion. Ex- periments are performed to study the energy loss of heavy ions and its charge in plasma. Dielectronic recombination is predicted to be a dominant process if free electrons are present.

This work was supported in part by the Commission of the European Communities in the framework of the Asso- ciation Euratom/IPP.

- 37 - ECLIM18: R-l-2

RECENT RESULTS IN LASER PRODUCED PLASMA STUDIES AT THE SERC CENTRAL LASER FACILITY M.H. Key RAL

Progress in the development of the VULCAN neodymium glass and SPRITE KrF laser systems is summarised and recent experimental results in the fields of XUV laser research. X-ray source applications, physics of dense plasma and physics of laser fusion are highlighted, including recent demonstration of laser amplification at 8.1 nm.

- 38 - '•'.-Lih',13: R_i_3

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- 39 - ECLIM18: R-l-4

ULTRA-HIGH PRESSURE, DIRECT-DRIVE, ABLATIVE COMPRESSION EXPERIMENTS. R. L. McCrory University of Rochester Laboratory for Laser Energetics 250 East River Road , Rochester, New York, 14623, U.S.A. Direct-drive laser-fusion expx iments presently being conducted at the University of Rochester's Laboratory for Lasei Energetics are addressing key issues in pellet compression and heating: laser energy absorption and coupling efficiency to the target and fuel, target preheat arising from parametric instabilities, and the drive uniformity required to avoid hydrodynamic instabilities and obtain high fuel compressions.

In experiments conducted since the 17& ECLIM, LLE experiments have achieved the highest pressure for direct-drive implosions: over 1010 atmospheres. These high- temperature, high-density direct-drive implosions have achieved conditions comparable to those achieved elsewhere in 10-20 kJ laser driven implosions employing radiation drive.

Results from these experiments will be presented. The significant progress made in high-density experiments is the result of careful beam control and measurement. Results of both phase and intensity measurements on full power OMEGA beams, with an accuracy of A/15 will be presented. Beam calorimetry is now used to measure individual beam energies to better than +2% and beam-to-beam energy imbalance is less than ±4% rms. Beam pointing accuracy is ±10 Jim rms1. Two dimensional hydrodynamic simulations, together with a three-dimensional beam superposition code to calculate refraction and absorption of the incident radiation, are in agreement with recent experiments with the improved beams of the OMEGA laser.

Experimental results on target experiments include a full complement of core- diagnostics which measure the neutron flux, and spectrum; the shell and fuel pAR and pR using nuclear activation2 by using the secondary reaction products and knock-on-ion spectrometry; and the spatial extent of the bum region by alpha-particle imaging. Streak imaging of the self-emission of the imploding targets has been used to measure the radius vs. time trajectory of the imploding capsule which is sensitive to the mass ablation rate and thermal transport within the target. These measurements are also used to infer shell uniformity of the implosion or hydrodynamic disruption as a function of laser drive uniformity. Simulations based on 2-D ORCHID and 1-D LILAC codes are used to explain the observed thickness of the emitting region.

1. Kessler, T. et al., Technical Digest, Conf. on Lasers and Electro Optics, '86, IEEE, San Francisco (1986) 238. 2. Richardson, M.C., et al., Phys. Rev Lett.. 56, (1986) 2048.

- 40 - ECLIM18; 1-1-1

PARTICLE SIMULATION OF NONLINEAR RESONANCE ABSORPTION

S. Huller, P. Mulser Institut fur Angewandte Physik, Technische Hochschule Darmstadt, FRG

The electromagnetic wave propagation in media with refractive index modulated by light pressure or electrostatic waves is investigated analytically. The numerical calculations of interacting high- amplitude electrostatic and electromagnetic waves confirm these predictions. Excitation and propagation of Langmuir waves in flat as well as in steep plasma density profiles are calculated and discussed with emphasis on nonlinear Landau damping, including particle trapping and wave breaking. Results obtained from particle simulations show the spatial particle distribution and energy partition in a relevant parameter domain. The expression for the current density involves additional contributions from nonlinearly interacting plasma waves. These are taken into account, thus resulting in an extension of Ohm's law. Finally, the dynamics of the ion profile is also included, and its reaction to the wave propagation is investigated.

-100 0 Fig.1: It shows 8 humps of an Fig.2: Nonlinear evolution of the electron plasma wave propa- plasma wave is accompanied by the gating into the underdense production of trapped particles region (z > 0). with velocities close to the local phase speed of the wave, v,, = w/k. Both figures are snapshots of the phase space of particle simulation. The plots show the particle velocities normalized to the speed of light vs. the spatial coordinate z which is given in units of the Debye length at the critical density, xn - 41 - ECLIM18: 1-1-2

HOT ELECTRON GENERATION IN LASER-PRODUCED PLASMA V.B. Rozanov, S.A. Shumsky Lebedev Institute, Acad. Sci. USSR

- 42 - ECLIM18: 1-1-3

ADVANCES IN LASER FUSION AT DENIM

G. Velarde, J.M. Aragones,, J. J. Honrubia. J.M. Marti'nez-Val, E. Mfnguez J.L. Ocana, J.M. Perlado, P.M. Velarde

Instituto de Fusion Nuclear (DENIM). Pe Castellana 80,28046 Madrid, Spain

The research activities in laser fusion at DENIM are focused mainly in the target physics, simulation and understanding of experiments. To this end, we have recently developed several models and numerical tools for the characterization of the laser-plasma interactions and the target physics analysis. Specifically, we have studied the stimulated Raman scattering (SRS) by means of the relativistic fully- electromagnetic particle-in-cell WAVE codeO) as well as by simple semianalytical models. The results show that the level and spectrum of the hot electrons produced by SRS agree with the reported results.

From these PIC simulations we adjust the coefficients for our ray-tracing package, that includes 2D and 3D cases and is coupled to a single fluid 3T hydro code(2). In addition, a PIC 2D hydro code has been also developed to deal with asymetries and non-uniformities of the illumination, as well as to handle the mixing of materials.

Finally, the Nerst advection and its effects on thermal conduction have been analyzed(3) by means of the implicit ANTHEM code(4).

In this paper, the results of PIC simulations, the assymetry studies and the abovementioned models will be presented together with the comparison of our ray-tracing-hydro package simulations with the simulations^) and experiments perfomed at ILE (Osaka, Japan) with the GEKKO XII laser.

REFERENCES

1.- D. Forslund, "Fundamentals of plasma simulation" LA-UR-85-413(1985) 2.- G. Velarde et al. Laser and Particle beams, 4,3 & 4 (1986) 3.- P.M. Velarde, R.J. Mason, work performed at LANL (1986) 4.- R. J. Mason "An Electromagnetic Field Algorithm For 2-D Implicit Plasma Simulation" LA-UR-1391 (1986) 5.- J.M. Perlado, K. Nishihara, work performed at ILE-Osaka (1986)

- 43 - ECLIM18: 1-1-4

ON THE ENERGY CUMULATION LIMITS UNDER LASER COMPRESSION OF MATTER E.G. Gamaly Lebedev Institute, Acad. Sci., USSR

- 44 - ECLIM18: 1-1-5

ECLIM 87, MAY 1987, PRAGUE

Volume Ignition of Laser Driven Fusion Pellets and Double Layer Effects

H. Hora, L. Cicchitelli, M. P. Goldsworthy, R. S. Ray, R. J. Stening and H. Szichman

Department of Theoretical Physics University of New South Wales, Kensington, 2033, Australia.

The realization of the ideal volume compression of laser irradiated fusion pellets (by C. Yamanaka) opens the discussion of the possibility for an alternative to the long years discussed spark ignition in inter- tial confinement fusion. While Yamanaka compression is projected towards densities only of 30 times of the solid state at present, this is considered as a critical point compared with the spark ignition for densities close to 1000 of the solid state.

Since we found the volume ignition at stagnation free volume compression in 1978, we re-evaluated these certain fusion gains and find gains for DT at compressions 30 to 50 times of solid state only which compare with 1000 times compression at central pellet spark ignition. Further analysis between both regions is given in view of recent results on double layers and related processes.

- 45 - ECLIM18: 1-1-6

MUONIC SUPERDENSE MATTER T. Tajima Department of Physics and Institute for Fusion Studies The University of Texas at Austin, Austin, Texas 78712

A possible method of creation of superdense and superhigh energy density matter with approximate atomic density 4 X 1029 cm"3 is suggested. A pulsed beam of 10s muons, with duration 3 x 10~6 sec is shone on a liquid hydrogen of volume ~ (300A)3. A muon charge-exchanges with an electron in a hydrogen atom: with enough muonic hydrogen atoms they begin to nucleate into a condensed state. The muon beam should be cooled by the ionization process and channeled through crystal axes before irradiation on the hydrogen specimen. When magnetic fields are present upon irradiation, the fields may be enhanced up to 109 Gauss. The method for generating an appropriate muon beam may be provided by the crystal channeling and X-ray shaping of the muon beam.

- 46 - ECLIM18: 0-1-1

ANOMALIES IN THE STIMITATED RAMAN SPECTRUM FROM LASER-PRODUCED PLASMAS

T.J.M. Boyd, G.A. Gardner and G.A.Coutts

Department ot Physics,. University of Wales, (ICNW, Bangor, Wales, U.K.

Experiments over a number of years have confirmed some of the characteristics of the convective Raman (SRS-C) spectrum. At the same time virtually all experiments show features of SRS-C at variance with the predictions of conventional theory. One widespread source of disagreement is over thresholds where several experiments have reported scattered light within a wavelength band between Ao and 2AO (Ao is the wavelength of the incident light) but appearing at the same threshold intensity as for absolute Raman (SRS-A) light. Theoretically one expects the SRS-C threshold to exceed that for SRS-A.

Another persistent conflict between theory and the observed spectra is the cut-off in the scattered light spectrum at around l.5Ao. In view of these puzzling features of SRS spectra, Simon and Short [l] proposed a model based on the assumption that the scattered spectrum is not SRS light as such but is due instead to enhanced Thomson scattering from plasmas in which there is a population of suprathermal electrons. Tn this model laser light is scattered from plasma waves driven unstable by the bump-on-tail instability, the reversed slope velocity distribution being attributed to bursts of hot electrons moving out from the quarter-critical density surface where they may be generated by two-plasmon decay or SRS-A instabilities.

We have carried out a series of simulations in which a light wave propagates through a plasma characterized by two electron temperatures and in which the fraction of suprathermal electrons varies between 0 and 0.05. With a hot-electron population unstable plasma waves are generated and saturate early in the simulation. The results obtained show that enhanced Thomson scattering may account for the emission observed in at least some experiments and confirm the contention by Simon and Short that the Thomson scattered light is not especially sensitive to the width of the suprathermal electron feature.

tn their model calculation Simon and Short did not take account of the effect of the incident light on the plasma. However results from simulations in which the SRS-C growth rate was large indicate that emission from the plasma is reduced in the presence of a population of suprathermal electrons. We have examined the effect of a finite quiver velocity vo on the enhanced Thomson spectrum as a function of the suprathermal electron population and shown how the wavelength bands can be affected.

[1] Simon, A. and Short, R.L., Phys. Rev. Lett. 53, 1912 (1984), - 47 - ECLIM18: 0-1-2

PROPAGATION AND DETUNING EFFECTS IN PLASMA BEAT-WAVE GENERATION

S-J. Karttunen Technical Research Centre of Finland, Nuclear Engineering Laboratory, SF-00181 Helsinki, Finland

R.R.E. Salomaa Helsinki University of Technology, Department of Technical Physics, SF-02150 Espoo, Finland

The previous temporal treatment of the beat-wave problem is extended to a space-time dependent system, which can be solved analytically. The model includes full cascading of the electromagnetic modes, collisional damping and relativistic frequency shift of the plasma wave and detuning from exact resonance. In the relativistic region strong amplitude modulations of the plasmon occur provided that the laser pulse length is longer than the modulation period. Wake formation of the beat-wave can be controlled by the detuning and the pulse length. Electro- magnetic cascading proceeds with the pulse propagation, the spread of the spectrum being proportional to the propagation distance and the plasmon amplitude. The amplitude modulation of the plasmon is observable in the EM-spectrum as 'breathing' which provides an excellent diagnostic method for beat-wave experiments. The density variation regarding detuning, which can be 2 2/3 tolerated, scales as (IX. ) • Typically a density deviation of few percents from the exact resonance are allowed in CO_-experiments. With submicron wavelengths, however, an extremely accurate density control is required for beat-wave generation. 1. S.J. Karttunen and R.R.E. Salomaa, Phys.Rev.Lett. 56, 604(1986).

- 48 - ECLIM18: 0-1-3

ELECTRONS ACCELERATION UNDER RESONANCE INTERACTION OF LASER BEAM WITH INHOMOGENEOUS PLASMA

N.S. Erokhin, S.S. Moiseev, R.Z. Sagdeev

Institute for Space Research, Academy of Sciences of the USSR, 117810, Profsojuznaya Street 84/32, Moscow, USSR.

At present paper the peculiarities of the charged particles resonance interaction with strong electromagnetic waves in the inhomogeneous plasma are considered!1»2|. IVe analyse the following problems: conversion of the fast electromagnetic waves into the slow longitudinal waves in the weakly inhomogeneous plasma with account of the geometrical optics breaking region, resonance amplification of the longitudinal wave fields, possibility of the charged particles entrainment by slow waves and particles acceleration in the inhomogeneous plasma with embedded quasistatic magnetic field |3-S| which easily generated in laser plasma. The criterion is given on parameters of plasma and the electromagnetic radiation, and the plasma inhomogeneity under which the fast particles tails are generated as it is observed in an experiments. For laser plasma conditions one has evaluated the acceleration region scales and the energy gain of the accelerated particles, and ratio between the quasistatic magnetic field and laser beam field. The influence of nonlinear processes on the electrons entrainment and acceleration in the inhomogeneous magnetoactive plasma is discussed.

1. S.S. Moiseev, V.V. Mukhin, V.E. Novikov, R.Z. Sagdeev. Doklady Acad. Sci. USSR, 285, 346 (1985). 2. S.S. Moiseev. Plasma Astrophysi cs (Abstracts of reports of International conference at Sukhumi), Sukhumi, p.133 (1986). 3. R.Z. Sagdeev, V.D. Shapiro. Pis'ma JETF, 1_7, 389 (1973). 4. T. Katsouleas, J.M. Dawson. Physical Review Letters, 51, 392 (1983). 5. B.E. Gribov, R.Z. Sagdeev, V.D. Shapiro, V.I. Shevchen- ko. Pis'ma JETF, 42, 54 (1985).

- 49 - ECLIM18: 0-1-4

FLUX CONDUCTION EFFECT ON LASER-INDUCED DENSITY PROFILE AND PLASMA ABLATION NEAR PLASMA RESONANCE LASER.

D.P.Singh, M.Vaselli and R.Singh

Istituto di Fisica Atomica e Molecolare del C.N.R. Via del Giardino, 7 56100 PISA, Italy

* Physics Dept. Indian Institute of Technology, New Delhi 110016 India.

The flux transport effect on the radiation induced plasma density profile and ablative flow outside the resonance layer in steady state in one dimensional spherical geometry is studied. The opposing radial plasma thermal gradients on both sides of the plasma critical layer put lower and upper bounds on the flux limit in the underdense and overdense regions respectively. The numerical predictions conclude the existence of plateau like plasma density profile rather than overdense bump formation in the underdense plasma. The plasma density profile, though retaining its shape, becomes more pronounced as the heat flux is increased. However, the length of the plasma density plateau is found to be quite small as compared with the isothermal case.

- 50 - ECLIM18: 0-1-5

TWO-DIMENSIONAL LAGRANGEAN MODELLING OF PLANAR TARGETS.

J. Virmont, B. Faral.

Ecole Polytechnique and GRECO I. L. M. 91128 Palaiseau Cedex, France.

A 2-dirnensional Lagrangean code has been developped, to model the relatively cold regions in laser-irradiated targets. It includes hydrodynamics and one energy equation. The pressure is given by Sesame tabular equations of state. The geometry is cylindrical around the laser beam. The laser is modelled by an external pressure, with a prescribed radial and temporal dependance. To model the ablation, material is progressively removed in front of the laser, at a velocity consistent with one-dimensional results.

The numerical scheme is basically that proposed by Wilkins. Some attention has been paid to the behaviour near the axis. An improved prescription for the artificial viscosity has been developped, which efficiently prevents cell distortion, without any rezoning.

Applications to various situations are presented, with comparisons with the experimental results obtained in our group : the radially- and temporally-resolved emergence of a shock at the rear of a thin foil; the stretching of a foil during its flight; and particularly the collision of the accelerated foil with a second thin foil, with a variable spacing.

- 5i - ECLIM18: 0-1-6

Uniformity of Illumination in Direct-Drive Laser Fusion by W. Seka, T.J. Kessler, S. Skupsky, F.J. Marshall, P.A. Jaanimagi, M.C. Richardson, J.M. Soures, C.P. Verdon, and R. Bahr Laboratory for Laser Energetics University of Rochester Rochester, NY 14623-1299

Direct drive laser fusion requires a high degree of uniformity of illumination on the target in order to succeed. Two-dimensional hydrodynamic simulations indicate that a 1 per cent rms illumination uniformity on target will be required in future high density/high yield experiments. In an effort to approach these requirements experimentally we have embarked on series of experiments employing a variety of diagnostic techniques which allow us to define and measure our present illumination uniformity, both in terms of optical and x-ray equivalent target plane measurements, and in terms of ultimate performance characteristics and performance limits of our present laser facility. The report will discuss these results and implications as well as some of the novel experimental and data reduction techniques.

This work was supported by the U.S. Department of Energy Office of Inertial Fusion under agreement No. DE-FC08-85DP40200 and the Sponsors of the Laser Fusion Feasibility Project at the Laboratory for Laser Energetics.

- 52 - TUESDAY

MAY 5 ECLIM18: R-2-1

ACTIVITY RELATED TO LASER I.C.F. AT 0.26 MICRO METRE, AND HIGH INTENSITY LASER APPLICATIONS

E. Fabre

Ecole Polytechnique, Palaiseau

Current activity will be presented concerning laser plasma interaction studies in homogeneous plasmas, energy transport, high pressure generation by shocks and its amplification, result on multibeam implosion experiment at 0.26 micro metre. Finally will be presented also some current activities on X-ray laser studies, laser particle acceleration and applications of shocks and X-ray sources to material processing.

- 55 - ECLIM18: R-2-2

PROBLEMS IN DENSE PLASMA DIAGNOSTICS A-S. Shikanov Lebedev Institute, Acad. Sci., USSR

- 56 - ECLIM18: R-2-3

LOW PREHEAT IMPLOSION EXPERIMENTS WITH CRYOGENIC FUEL TARGETS J- T* Larsen KMS Fusion, Inc., P.O. Box 1567, Ann Arbor, MI 48106 USA KMSF performed its first cryogenic fuel implosions in 1977 and achieved compressed fuel densities in the range of 4-7 g/cm3. A second series was performed in 1982 with a more extensive set of diagnostic instruments, where we demonstrated an improved compression with short wavelength (0.53 ym) laser light, and when the fuel configuration was a solid layer rather than a gas-filled target. Computer simulation of those shots showed the fuel was pre- heated to about 15 eV before the Pdv' work was done. The simulations showed the preheat to be attributable to a strong shock wave penetrating the fuel and heating it by viscous processes. The shock wave was generated by the rapidly rising laser pulse creating a multi-megabar pressure at the "ablation surface". By reducing the strength of the shock wave to approximately 0.5 Mbar, the fuel would be heated to only 1 or 2 el/ and thus remain at near solid density long enough for the PdV work to begin. This is accomplished by a precisely controlled, slowly rising laser pulse. By the end of the laser pulse, whose duration is approximately 1 nsec, the intensity must rise to a sufficient level to provide the 50 to 100 Mbar driving pressure. Computer simulations also showed that cryogenic fuel in a uniform layer, low atomic number (polymer) shells, and short wavelength laser light in a symmetric and uniform illumination were required. The illumination system employed two nearly spherical mirrors in a double-bounce configuration to convert the two laser beams of Chroma into a uniform illumination pattern on a spherical target located at the common focus. In 1985-86, we brought all of these ingredients together for an intensive series of target shots to verify our predictions about the effect of preheat on target compression. Of the more than 70 good shots, a few yielded excellent data which indicate a low preheat implosion was achieved. Our primary diagnostic was an x-ray backlighter in conjunction with an x-ray streak camera. One dimensional, temporally dispersed information was recorded which provided an excellent record of the implosion trajectory. Numerical simulations of selected target shots show excellent agreement with the experimental data. Because only "one-dimensional" data were recorded by the streak camera, there is no direct confirmation of a spherical compressed core. Assuming such a configuration was achieved, an increase in fuel density above the 1982 results would have been produced. In addition, some shots, particularly on those targets with high aspect ratios, show an anomalous central x-ray emission. This is believed to be a result of shell breakup during the implosion phase and may be the first direct measurement of the Rayleigh- Taylor instability in spherical geometry. Prepared for the Department of Energy under Contract No. DE-AC08-82DP40152.

- 57 - ECLIM18: R-2-4

RECENT ADVANCES IN LASER FUSION C. Yamanaka ILE, Osaka University

- 58 - ECLIM18: P-l-1

PHOTON STATISTICS OF NCXCLASSICAL RAI/IATIOE IS FCUR- WAVE MIXING V.Pcfinova Joint Laboratory of Optics,Falacky University, Leninova 26,771 46 01omouc,Czechoslovakia

The statistical properties of radiation in four- wave mixing were discussed under different assump- tions making use of the short-length approximation [1] or the parametric approximation [2} or the short- time approximation [2,3] -A unified approach to the photon statistics of light in four-wave mixing including the losses based on the use of the generalized superposition of coherent fields and quantum noise [4-1 is adopted in this paper.Such a superposition descrio- es nonclassical state by means of "mean numbers of coherent photons" and "mean numbers of chaotic photons" taking on negative values.The generalized fokker-Planck equation appropriate to this process is used to obtain a set of recursive relations for the expectation value of the normal moment operators. This set of equations is interrupted in consistence with a model of the generalized superposition of coherent and chaotic fields providing equations of motion for unknown quantities in this model.A numerical solution of these equations enables to determine the photon number distribution and its factorial moments including fully quantum features of radiation such as its sub-Poisson behaviour and squeezing of vacuum fluctuations.The influence of the damping mechanism on the photon statistics and limits of this approximation are discussed.

1. J.Perina,V.Pefinovd,G.Sibilia,M.Bertolotti, Cpt.Comm. 49,285 (1984) 2. J.Baoer,J.Fefina,Czech.J.Phys.B 35,1146 C1985) 3. J.Bajer,J.Ferina,Acta Phys.Pol.A,in the press(i987) 4. J.Pefina,"Quantum Statistics of Linear and Nonlinear Optical Phenomena" D.Reidel-Dordrecht, Boston (1584)

- 59 - ECLIM18: P-l-2

ABSORPTION OP ENERGY BY GOLD INHOMOGENEOUS PLASMA PROM AN EXTERNAL SOURCE OP ELECTROMAGNETIC RADIATION Z. Sedlacek Institute of Plasma Physics, Czechoslovak Academy of Sciences, Pod vodarenskou vezi 4» CS-182 11 Prague 8, Czechoslovakia. B. Roberts Department of Applied Mathematics, University of St Andrewss St Andrevs KI16 9SS, Scotland.

Absorption of energy by a cold inhomogeneous plasma from an externally applied electromagnetic field is strongly enhanced when the frequency of the driving field equals the frequency of the collective, expo- nentially damped mode of the plasma [2, 3]. This is shown by solving the model problem [4]J of forced oscillations of a plasma slab which is described by a singular second-order differential equation with a right-hand side. A full-wave solution is obtained in terms of continuum eigenfunctions of the plasma slab £1] and a formula is derived either for the total absorbed energy in case of an arbitrary (but square-integrable) time dependence of the driving field or for the absorbed power in case of a stationary stochastic driving force (which includes e.g. sinusoidal excitation). As a result of causality, the active and reactive parts of the absorbed power are Hilbert transforms of one another with respect to frequency. Relations to other kinds of rf plasma heating schemes, especially to the Alfven wave resonant absorption heating [ 5 , 6, 7], are discussed.

1. E. M. Barston, Ann. Phys. (N.Y.) 29_ (1964), 282. 2. Z. Sedlacek, J. Plasma Phys. 5 (1971), 239. 3. Z. Sedlacek, J. Plasma Phys. S (1971), 187. 4. I. C Rae, Plasma Phys. 24 (1^82), 133. 5. J. Tataronis, W. Grossmann, Z. Physik 26j_ (1973), 203. 6. W. Grossmann, J. Tataronis, Z. Physik 261 (1973), 217. 7. J. A. Tataronis, J. Plasma Phys. V£ (1975), 87.

- 60 - ECLIM18: P-l-3

Total Absorption of Unpolarised Radiation in a Stratified Plasma

S. Vukovic. R. Dragila and A. M. Smith

Laser Physics Centre, Research School of Physical Sciences, Australian National University, P.O.Box 4, Canberra, ACT 2601, Australia

We demonstrate that 100% absorption of an unpolarised monochromatic light can be achieved in a plasma with a density profile characterized by a presence of a cavity and a steep density gradient across the critical region. These profiles can occur in a laser produced plasma due to the radiation pressure effects.The conditions were found when both s- and p-polarisations of the electromagnetic radiation obliquely incident on the stratified plasma are totally absorbed at the same angle of incidence. The effect is due to simultaneous excitation of surface and guided modes which are eigenmodes of the considered plasma structure. When these modes are excited some additional conditions must be satisfied which allow for full compensation of all dissipative processes by the radiation energy inflow.

*Department of Physics, University of Waikato, Hamilton, New Zealand

- 61 - ECLIM18: P-l-4

STIMULATED RAMAN SCATTERING IN THE PRESENCE OF FILAMUNTATEON

H.C. Barr, T.J.M. Boyd and G.A. Coutts

University of Wales, Bangor, Wales, U.K.

We describe a model for stimulated Raman scattering in which both plasma density and laser intensity profiles have been corrupted by filamentation and which accounts for the interplay between the roles of the inhomogeneity, Landau damping and the self-focussing of the incident and scattered light waves. The model prescribes a sinusoidal density modulation transverse to the incident light.

The density modulation, through its effect on the plasma wave, reduces the Raman growth while the intensification of laser light within the filaments can reverse this to give modest increases in net growth. Both effects concentrate SRS at the density minimum where the density gradients are least and the laser light most intense. However, Landau damping is also strongest there and as the filament deepens this can dominate, strongly reducing growth and thereby leading to SRS occurring preferentially at locations higher up the filament wall. Ultimately, the densities at which SRS might occur and where the laser energy resides become mutually exclusive and then only stimulated Compton scattering remains.

In addition the scattered wave spectrum will be modified significantly in filaments which focus to sizes of the order of a skin-depth. Acting as waveguides they require higher frequencies for propagation and this, in turn, further restricts phase matching to scattered wave frequencies which can be well above the expected minimum frequency of UQ/2. This is consistent with behaviour seen in many laser target experiments. Finally, thresholds are sensitive to the details of filament shapes, information on which is not readily available from contemporary experiments.

- 62 - ECLIM18: P-l-5

THE RAMAN INSTABILITY: NON LOCAL EFFECTS AND THE TRANSITION BETWEEN ABSOLUTE AND CONVECTIVE REGIMES

H.C. Barr, T.J.M. Boyd and G.A. Coutts

University of Wales, Bangor, Wales, U.K.

Stimulated Raman scattering (SRS) from inhomogeneous plasmas admits two distinct regimes. Below the quarter critical density surface theory predicts that the instability is convective. The 2 threshold for bacXscatter is (vo/c) koli>l where vo is the quiver velocity, kj, the laser wave number and L the plasma scale length. Such a "threshold" is usually defined so that an amplification of e27T is achieved over the noise level. In practice this threshold has been relaxed to improve agreement between theoretical and measured thresholds but even so agreement is not yet acceptable. This regime is characterized as the SRS-C instability.

Near nc/4, or for sidescatter, the lightwave is trapped at its reflection point and the instability is absolute (SRS-A) with 2 3 a threshold for temporal growth (vo/c) (koL)*/ >l/ which is a less stringent condition than that for SRS-C.

The question naturally arises as to the nature of the transition between these two regimes. The SRS-C regime treats back and Forward scattering as distinct cases. Of course as has been recognized elsewhere these processes are not independent. For a given scattered frequency us the back and forward scattering resonances are in close proximity to one another, at densities which differ by

*2 = 12(Ve/c)& e 2 [S[i \z\ - * } [** [ - i Iff (i) nc * Luo I <*> J L «o J J with forward scattering occurring at the higher density of the two. Therefore if the laser light propagates into a plasma of increasing density the plasma wave amplified in the Raman backscatter may be subject to further amplification in generating forward scattered light. In turn if the plasma is overdense to this light it will reflect and again be subject to amplification at the Raman backscatter resonance. Such non-local effects can make the SRS-C instability absolute, resulting in lower instability thresholds. As the quarter critical density is approached the back and forward scattering instabilities are no longer distinct as is clear from (1) when a>8 - u>o/2.

To elucidate this transition and the interdependence of forward and backscatter we have solved numerically the full wave equations for SRS rather than on the one hand relying on the conventional WKB analysis for the convective case and on the other neglecting plasma wave propagation in the case of the absolute instability.

- 63 - ECLIM18: P-l-6

ROLE OF LANGMUIR WAVE NON-LINEARITIES

IN STIMULATED RAMAN SCATTERING (S.R.S.)

OOOOOOBOOOOO

G. BONNAUD

Commissariat & l'energie atomique, centre d'etudes de Limeil

B.P. 27 94190 Villeneuve-st-Georges (France)

D. PESME

Centre de Physique Theorique, Ecole Polytechnique

91128 Palaiseau (France)

The non-linear evolution of SRS is studied

numerically. A mode-coupling type code has been designed,

aimed at investigating the role of the coupling of ion

dynamics to SRS. Use of either the complete propagators

or envelope approximations can be made, making it possi-

ble to investigate separately each of the various effects

induced by ion dynamics (decay of plasma waves, stimula-

ted Brillouin scattering (S.B.S.), modulational instabi-

lity and collapse). Special interest is given to the role

of the nucleation of the plasma waves, by comparing the

SRS reduction induced by nucleation, with the SRS reduc-

tion due to the simple SRS/SBS competition and to the

decay of plasma waves.

- 64 - ECLIM18: P-l-7

18th EUROPEAN CONFERENCE ON LASER INTERACTION WITH MATTER (ECLIM) 4-8 May, 1987, Prague, Czechoslovakia

Nonstationary stimulated Brillouln scattering In the strong coupling case

Carlos MONTES » and Rene PELLAT 2 Groupement de Recherches Coordonnees (GRECO) "Interaction Laser-Matiere" da Centre National de la Recherche Scientifique (CNRS) 1 Laboratoire de Physique de la Matihre Condensee, Pare Valrose, 06084 N*ce Cedex, France, and Observatoire de Nice, B.P. 1S9, 0600S Nice Cedex, France 2 Centre de Physique Theorique, Ecole Polytechnique, 91188 Palaiseau Cedex, France

Nonstationary stimulated Brillouin backscattering of a laser pump wave, exhibit- ing nonlinear pump depletion when propagating in a long material medium (optical or plasma fiber), generates strong acoustic field modulation. The complete evolution equation for the sound wave (without the envelope approximation) is needed for describing the inertial response of the material in the strong coupling case. The strong sound pressure produced may explain the observed damage and even the mechanical fracture of an optical fiber supporting high laser flux intensities. This effect can be important too in laser electrons accelerators using plasma fibers, and in laser-plasma interaction experiments on inertial fusion devices, where a long-scale-length plasma surrounds the target.

- 65 - ECLIM18: P-l-8

BENARD INSTABILITY IN LASER-PRODUCED PLASMAS

D. Bassett, 0. Will!

Imperial College of Science and Technology, London SW7 2AZ, England

R. G. Evans

Rutherford Appleton Laboratory, Chilton, Dldcot 0X11 OQX, England

For the first time a fundamental convective fluid instability described by Benard has been observed in laser-produced plasmas.

Thin aluminium stripes coated onto a Formvar substrate were exploded using four frequency doubled (526 nm) 70 ps laser pulses generated by the Vulcan laser at the Rutherford Appleton Laboratory.

The line focus arrangement used for X-ray laser experiments ensured uniform illumination on targets 1.5 mm in length and 50 y wide with intensities of up to 10l5 w/cm2.

A multiframe optical probe, operating with five frames separated by 150 ps, diagnosed the instability. The probe, 15 ps long, was directed through the expanding plasma and the photographs taken were either straight shadowgrams or Schlieren images.

The ensuing images clearly show the formation of regular square structures indicating convective cells which last for several hundred picoseconds before returning to chaos.

The instability is created by the hot inner plasma pushing out through the colder surrounding material. Experimental evidence showing clearly the instability and theoretical interpretation will be illustrated in the presentation.

- 66 - ECLIM18: P-l-q

SECOND HARMONIC GENERATION FROM UNDERDENSE PLASMA

D.Giulietti*, G.P. Banfi**, F.Cornolti*, A.Giulietti, M. Lucchesi*, L.Nocera and Chen ZeZun***. Istituto di Fisica Atomica e Molecolare . . Via del Giardino, 7 56100 PISA, Italy *Dipartimento di Fisica - Universita di Pisa **Dipartimento di Elettronica - Universita di Pavia ***Istitute of Optics and Fine Mechanics - Shanghai -

Forward SHG from a plasma of density n ^.n /100 was e -§ -10 observed with an efficiency ranging from 10 to 10 13 2 The intensity of the foundamental was 10 W/ciri , but local increase was likely to occur due to self-focusing. SHG at 90° was orders of magnitude lower in the same conditions. Time resolved measurements showed SHG pulses much shorter than laser pulses. These findings are in agreement with the general features expected from SHG by strong density gradients and were compared with theoretical calculations in the far field approximation. Possible use of SHG detection in underdense plasmas as a diagnostics of filamentation will be discussed.

- 67 - ECLIM18: P-l-10

ROLE OF NORMAL MODES IN HARMONIC GENERATION

L Nocera

Istituto di Fisica Atomica e Molecolare (IFAM-CNR). Via del Giardino 7 56100 Pisa, Italy

We study the effects that excitation of normai modes has on the generation of harmonics in a plasma created by illuminating a solid target with a laser beam (the pumpj We assume the plasma thickness to be small when compared with the macroscopic size of the target and assimilate the plasma laver to a plane, one-dimensional slab of finite thickness, pump light impinges orthogonally on one side and electron density increases in a linear ramp-like fashion away from the illuminated side of the layer, up to supercritical values. First, we work out the linear normal modes for a set of radiative boundary conditions at the illuminated end As usual, products of normal modes give harmonic light. As the frequencies of the different normal modes are not in rational relation, the frequencies of the resulting harmonics are not multiples of the fundamental frequency of the pump light. The nonlinear evolution of the amplitude of the normal modes is then investigated using a Galerkin expansion. Special attention is devoted to a four-dimensional truncated system and to its bifurcations.

- 68 - ECLIM18: P-l-11

GENERATION OF THE HIGHER HARMONICS OP POWERFUL LASER RADIATION IN INHOMOGENEOUS PLASMA A.G.Litvak, A.M.Peigin, E.A.Chernova Institute of Applied Physics, USSR Academy of Sciences, 46 Uljanov Street, 603600 Gorky, USSR

When intense electromagnetic waves interact with plasma, the nonlinear properties of plasma with low inertia are very important in strong electromagnetic fields* It is shown that in inhomogeneous plasma the joint action of relativistic and electron nonlineariti.es may lead to effective generation of heating radiation harmo nics in the plasma resonance region. For example, this is typical of experiments with plasma subject to powerful radiation of a CO? laser [y with a wide (more than fourty harmonics; gradual spectrum of reflected radiation. We consider a model of one-dimensional linearly inhomogeneous plasma assuming that the electron oscillation velocity in the pumping field is high enoughxQ^/iRto*^VT (where e and m are the charge and mass of rest of electrons, respectively, and TT is the thermal velocity of electrons). It is shown that with relativistic nonlinearity being neglected, the gradual spectrum with z En~ h' ( ft is the number of the spectral harmonic) is generated at

In this case the trajectories of oscillating electrons in the plasma resonance region are intersected because of the electron nonlinearity. In Eq,(1) V is the collision frequency, 00 is the pumping field frequency, L is the characteristic scale of plasma inhomogeneity, c is speed of light, and #o -£o/e . The relativistic nonlinearity produces a small-scale modulation instability in the resonance region, which, in turn, leads to a lower threshold of harmonic generation and a wider harmonic spectrum,

1. R.L.Carman, C.K.Phodes, R,P.Benjamin, Phys,Rev,A, 1981, v,24, p.2649.

- 69 - ECLIM18: P-l-12

RESONANT EXCITATION T NONLINEAR LANGMUIR WAVES,

ELECTRON TRAPPING, AND WAVE BREAKING

A. Bergmann, H. Schnabl, P. Mulser Institut fur Angewandte Physik, Technische Hochschule Darmstadt, FRG

The excitation of high-amplitude Langmuir waves in an inhomogeneous plasma is treated in the geometry of the capacitor model. Steepen- ing of the density profile, as well as increasing the adiabatic exponent Y from 1 to 3 results in a faster excitation of the wave and in a shorter time for the wave to lose its periodicity ( wave breaking ). If the excitation strength - given by the ratio of driver intensity to electron temperature - is small enough quasistationary waves can be excited in a weakly inhomogeneous plasma which are similar to those in a homogeneous plasma. The dispersion relation of such nonlinear Langmuir waves is amplitude dependent, thus resulting in a dispersion band rather than a dispersion curve in the (i»),k) diagram. Numerical calculations show that the steep increase of pressure is responsible for a definite limit in the amplitude of a Langmuir wave in the warm plasma. For the steady state in the homogeneous plasma an integral expression describing this limit was found. If a fraction of the electrons is trapped the electron density limit is lowered and the dispersion relation is strongly changed. The plasma frequency is considerably decreased; e.g., in the presence of 20% of trapped electrons the frequency is maximally lowered by 40%.

0.00 0.05 0.10 0.00 0.08 0.10 k/k0 k/k0

Dispersion bands for a Langmuir wave with 0%, 5%, 10%, 20% of trapped electrons. B6: Bohm-Gross curve; upper boundaries: curves at maximum amplitude.

- 70 - ECLIM18: P-l-13

STRUCTURE STABILITY OF THE WAVE COLLAPSES IN MEDIA WITH LOCAL NOHLINEARITY A.G.Litvak, E.I.Rakova, A.M.Sergeev Institute of Applied Physics, USSR Academy of Sciences, 46 Uljanov Street, 603600 Gorky, USSR

A variety of physical systems with wave collapses is described by a three-dimensional Schrodinger equation: -UJt + A serious obstacle to studying the field self-compression stability in terms of Bq.(1) is high dimensiona- lity of space needed for the observation of fragmentation of the fundamental spherically symmetric mode of collapse. The obstacle is removed by using a one-dimensional equation 1

6 which is similar to the initial problem (1) as to asymptotic behavior of the field. Study of this equation reveals the structure instability of the quasi-classical collapse 2 and the determining role of "weak" wave collapses in the dynamics of nonlinear systems. Analytical and numerical investigations show that the wave bunches produced by the fragmentation of a quasi- classical structure

evolve to a "weak" collapse: (oty * ut.-ti*» J This leads to zero-energy singularities. Analysis of the spatial structure of the "weak" collapse mode shows that in a coordinate system compressed together with the wave bunch this mode corresponds to stable distribution of the field in the form of a dissipative soliton. 1. G.Pelletier. Phys.Rev.Lett., 1982, v.49, p.782. 2. V.E.Zakharov, E.A.Kuznetsov, S.L.Musher. Pis'ma v ZhEfTP, 1985, v.41, p. 125.

- 71 - ECLIM18: P-l-14

DYNAMICS OF THE WAVE BEAMS IN MEDIA WITH RELAXATION NONLINEARITY V.A.Mironov, A.M.Sergeev, A.V.Khimich Institute of Applied Physics, USSR Academy of Sciences, 46 Uljanov Street, 603600 Gorky, USSR The wave processes in media with inertial nonlinearity have attracted widespread attention through the experimental study of the action of powerful short-pulse radiation on matter, A specific type is media with relaxation nonlinearity 1,2 described by the dynamic equation for perturbation of parameter n (concentration, temperature, etc.) under the action of high-frequency field with amplitude A: { The best known examples (in plasma and condensed matter) are local relaxation: F-~n+ IAIZ and diffusive relaxation: F=Aj.n -A^lAi*. If the characteristic time of variation of is more than the time of wave propagation through the nonlinear medium, then a stationary approximation is valid for the amplitude A, which leads, in the case of wave beam, to a parabolic equation: -i*A +&J.A +nA=O (2) The set (1), (2) has a class of self-similar solutions which describe localized (in cross-section) wave beams collapsing with time, or dynamic electromagnetic filaments* The following solutions are validr

for local relaxation, and fi n- for diffusive relaxation. Note that the power canalized in a dynamic filament can exceed substantially the critical power of self-focusing in a similar system with stationary nonlinearity. The spatial structure of the filaments is found, the regions of their appearance are specified and stability of self-compression is proved. 1. V.A.Petrishchev, V.I.Talanov. Kvantovaya elektronika, 1971, No.6, p.35. 2. P.Shimizu. IBM J.Res.Develop., 1973, v.15, p.285.

- 72 - ECLIM18; P-l-15

THE SELF-FOCUSIKG INSTABILITY OF A LASER BEAM IN A MONHOftiGGEHEOUS PLASMA AT THERMAL NONLINEARITY N.S. Erokhin, and A.P. Fadeev Keldysh Institute of Applied Mathematics USSR Academy of Sciences 125047 Moscow, Miusskaya sq., 4, USSR A fine structure of the laser plasma obtained in experiments ox latest years testifies on thermal nonlinearity of laser beams, which manifestsiin the form of the bean self-focusing and filaraentation 1-2 • Aside from violating the homogeneity of the pallet radiation, it contributes to generating small-scale magnetic fields that affect essentially the transport processes 3 • For the laser plasma some estimates of the thermal self-focusing instability parameters are given, for example, in 4,5 • This paper is dealt with. analytical and numerical investigations of nonlinear structures forming in a nonhomogeneous plasma as a result of the self-focusing beam instability due to the nonlocal thermal nonlinearity. In the non-aberration approximation an equation is derived for the beam width, and its solutions are investigated. The conditions are formulated when the plasma inhomogeneity takes a considerable effect upon the laser beam self- -focusing, and the self-action dynamics in the nonhomogeneous plasma is studied. By using numerical integration of the parabolic equation for the beam field amplitude the nonlocal thermal self—focusing of the Gaussian and super-Gaussian beams in the nonhomogeneous plasma is analized, the self-focusing dynamics depending on the beam parameters, the plasma and the inhomogeneity type is considered. It is shown that the results of numerical simulation differ from those of the non-aberration approximation, and that a nature of the thermal nonlinearity nonlocality is fundamental for the self-focusing dynamics. An analysis is carried out for the nonlinearity saturation process in the focal region aa well as for reaching a maximal amplification of the laser beam field near focuses. The plasma layers acting as focusing lenses are discussed.

1. I.V. Alexandrov, N.G- Basov, A.A. Galichy et al., Pis'ma v ZhETF, 38, 12 (1983). 2. O.Willi, P.T. Rumsky, L.Lin, "Laser Interaction and Related Plasma Phenomena", M.Y.: (1984). 3. CM. Max, Laser Plasma Interaction (Universite de Grenoble Les Houches), Narth-Holland Publishing Company, A: (1982). 4. K.Estabrook, W.L. Kruer, D.S. Bailey, Phys.Fluids, 28, 1 5. N.S. Erokhin, A.P. Fadeev, Preprint, Keldysh Inst.Appl.Math., USSR Ac.Sci., N 203 (1983). - 73 - ECLIM18: P-l-ifi

CAPTURE AND ENTRAIMENT OP ELECTROMAGNETIC WAVE PACKETS INTO SUPERCRITICAL REGIONS OP INHOMOGENEOUS PLASMA BY ION-SOUND WAVES E.M.Gromov and V.I.Talanov Institute of Applied Physics, Academy of Sciences of the USSR, Gorky, USSR A new mechanism of capture and entrainment of electromagnetic (em) field packets into inhomogeneous plasma regions where the local value of the plasma frequency exceeds the frequency of the radiation incident on the plasma (supercritical regions) is considered. The penetration into supercritical region is due to em field states associated with intense ion-sound waves in the inhomogeneous plasma and entrained by these waves into dense plasma layers. The frequency of the entrained states increases monotonically with time, while the lifetime of the entrained em field is determined in this case by three factors: tunnel "luminescence" of the em field from the localization region, nonlinear transformation of the ion-sound wave energy into the entrained em field, thermal losses caused by collisions of plasma particles. The efficiency of excitation of the entrained em field states by em radiation of the given frequency incident on the plasma is determined. The lifetime and the depth of the entrained em field penetration into dense plasma layers are found. The possibility of the em field to penetrate into the plasma layers with the concentration several times higher than the concentration in the region of the turning point of the radiation incident on the plasma is shown.

- 74 - ECLIM18: P-l-17

-U^JAL-^X -L v», lij j. _Lj* - t^i.^t *. _^j _ J.J.**!/ j i-O _L J. O-J

ALibIik , V.P.Shvets , * 3cieii'Lix"ic Council on Coup lex Problem "Cybernetics", Ac. Sci., Moscow, USbR ••Institute of Automation and iillect.rorr.etrj', Siberian Branch Ac. Sci., Novosibir^lc, USSR

Under typical parameters of laser plasma the turbulence excited due to parametric instabilities is strong. .For the most part of the turbulence zone, oscillations are excited with the lar^e wave numbers, spaced closely enough to the ntronj Landau damping re0ion. in this case even small widening of the spectrum, occurin0 at the initial staje of the modulation instability, resuls in an effective waves damping and electrons acceleration. It in particular means that for the lar^e mismathes of the pump wave frequencies from the plasma frequency one-dimensional model is adequate. In this paper particle simulation of the strong wave - plasma interaction is carried out. Exci- ting oscillations accelerates the electrons, stretching distribution function tails. Those tails creates additional damping in the excitation zone, V/hen the tails achieve the excitation zone boundary, which corresponds to the least wave number values, the instability is ceased and it determines the upper bound of electrons energy.

- 75 - ECLIM18: P-l-18 FLUX-RELAXED THERMAL CONDUCTION AMD ITS APPLICATION TO ELECTRON HEAT TRANSFER

£•1* Levanov, E.N.Sotsky

Keldysh Inst* of Applied Mathematics, the USSR Ac.of Sex. 125047, Mbacow, USSR.

Classical presentation of heat flux as the product of conductivity de and the temperature gradient (Fou- rier's law) is often invalid in case of intense heat transfer* Kinetic approaoh is not always acceptable if a wide-scale computational experiment is carried out* In view of everything mentioned above, the problem of search and investigation of other mathematical models, describing heat transfer, is quite important. One of such models, which has been known since J.C.Maxwell, is based on the assumption, that heat flux relaxes to its quasiequilibrium state, defined by Fourier's law, with finite relaxation time f . In this paper we examine this mathematical model* Heat transfer is examined both in fixed medium and in compressible gas. Nonlinear dependence of conductivity X and relaxation time of heat flux T on temperature and dencity is taken inwo account* The case of such dependence, corresponding to electron thermal conduction of fully ionized plasma, is given special attention. Existence of additional discontinuity is revealed in solutions of corresponding systems of differential equations, this jump being connected with this particular method of describing heat transfer* The influence of heat flux relaxation on the 00 called regime* of temperature waves of the first and the second type (TW-I and TW-II) is also studied. Some questions, connected with numerical aolution of hyperbolic type thermal conduction equations, are considered* This very model is compared with other mathematical models of intence heat transfer in high temperature plasma.

- 76 - ECLIM18: P-l-19

THE EFFECT OF SPACE-VARIABLE HEAT CONDUCTIVITY COEFFICIENT OK THE LASER CORONA BASIC PARAMETERS E.G.Gamaly, A.E.Kiselev P.N.Lebedev Physical Institute, Academy of Sciences of the USSR, Leninsky pr. 53, 117924 Moscow, USSR

Under certain conditions the heat flux in the laser corona can significantly differ from the one with classical heat conductivity coefficient. Basing on the stationary model of the spherical laser target corona /1/ we have considered in the present paper the effect of the heat conductivity decrease on the basic plasma parameters : the temperature of the radiation absorption zone T ; the distance between the critical R and ablatioPi1* R > surface; the shell evaporatxon rate m and x-ne ablation pressure P . It is assumed that heat conductivity preserves its diffusion character, however, the electron heat conductivity coefficient within the region between the radiation absorption zone and the ablation surface is smaller than the Spitzer one. Heat conductivity in the external layers of the corona is considered classical. Analytical dependences of the noted corona characteristics T , R , m, and P on the parameter 0. and the intensity ox the absorbed laser radiation have been obtained. So yie have shown that within the intensities 1013-10^V//cm2 the decrease of the electron heat conductivity affects mainly the critical radius, other corona parameters being changed slightly: || j is tne where6Q~QD3BO *{ /27 Pci ^ parameter defined through the target parameters and the intensity of the incident radiation per unit of the solid angle /1/; pLX , the critical density; M and Z, the charge and mass of the shell matter; CL is the value showing how much less than the Spitzer one is the heat conductivity coefficient in dense layers of the corona. The model has been compared with experimental results /2/.It is shown that the calculated and experimental dependences R and m can be matched only by decreasing the heat conductivity coefficient in the region between the ablation and critical surfaces by 10-30 times

LYu.V.Afanasiev, E.G.Gamly, O.N.Krokhin,V.B.Rozanov. ZhETP 71 (2), p.594-602 (1976). 2.VJ.W.Fechner, C.L.Shepard, Gar.E.Busch, R.J.Schroeder and J.A.Taruin. Phys.Fluids 27(6), p.1552-1560 (1984).

- 77 - ECLIM18: P-l-20 NON-UNIFORM ILLUMINATION EFFECTS IN LASER IRRADIATED - SPHERICAL PELLETS

M. Perez-Saborid*, A. Barrero* and J. Sanz**

* E.T.S.I. Industriales. Universidad de Sevilla, 41012 Sevilla, Spain. **E.T.S.I. Aeronauticos. Universidad Politecnica de Ma- drid, 28040 Madrid, Spain.

The quasi-steady expansion of a plasma ablated — from a spherical target under weakly non-uniform illumi^ ira<}) nation 1 = 1^ + ^ I^d,*) P™ 2 and positive for 1=1. The 1>2 rank is unstable since any perturbation in the absorbed intensity produc es refraction resulting in perturbation feedback. Re— suits for the planar case have been obtained elsewhere.

1. J.R. Sanmartln and A. Barrero, Phys. Fluids 21,1957, 1978. 2. J. Sanz, A.Linan, M. Rodriguez and J.R. Sanmartln, - Phys. Fluids 24, 2098, 1981. 3. J.R. Sanmartin, J. Sanz and J.A. Nicola's. Submitted to Phys. Rev. Lett.

- 78 - ECLIM18: P-l-21

3-D VLASOV EQUATION IN PLASMAS WITH STRONG HF FIELD AND LARGE SPATIAL GRADIENTS

M. Kalal* and I. Stoll

Faculty of Nuclear Science and Physical Engineering, Czech Technical University, Brehova 7, 115 19 Prague, Czechoslovakia

*) Present address: Laser Physics Center, Research School of Physical Sciences, Australian National University, Canberra, A.C.T. 2601, Australia

The 1-D perturbation method of solving Vlasov equation in plasmas with strong high-frequency fields and large spatial gradients [1] is extended into three dimensions.

The system of recurrent relations is derived which allows for an analytic solution to be found in the form of a sum of differential operators in velocity space with respect to the amplitude of HF fields as well as their spatial gradients.

Under the limitations imposed by other techniques [2] the method provides the same results. However, its main strength is the fact that it can be used beyond those limits.

Firstly the method is described and then applied to the calculation of some new results. As an example, take the case of a vacuum s-polarised pump wave. It is known that using this pump wave a steady-state magnetic field can be generated in plasmas but only in the collisional regime [3]. However, a new result of our current theory shows that even in the collisionless case a steady-state magnetic field will be generated purely by the ponderomotive force.

1. M. Kalal and I. Stoll, Phys. Rev. A 3J_, 4052 (1985) 2. P. Mora and R. Pellat, Phys. Fluids 22, 2408 (1979) 3. Yu. M. Aliev and V. Yu. Bychenkov, Fiz. Plazmy £, 80 (1980) [Sov. J. Plasma Phys. 6, 46 (1980)]

- 79 - ECLIM18: P-l-22

THEORETICAL INVESTIGATION OF LASER BEAM FILAMENTATION IN PLASMA CORONA J. Limpouch, G. Loncar Fac. Nucl. Sci., Tech. Univ. of Prague, Czechoslovakia I.G. Lebo, V.B. Rozanov Lebedev Institute, Acad. Sci. USSR

Ponderomotive and thermal filamentation of laser beams is studied, both numerically and analytically. In model studies there is revealed the role of following phenomena: plasma inertia, inhomogeneity, flow, non-local response and the interplay of ponderomotive and thermal processes. The plasma inertia is shown to strengthen filamentation at steep rise of laser pulse. The filamentation instability is found to be absolute for supersonic plasma flow in certain situations. Model of stationary corona with inverse bremsstrahlung absorption is introduced for investigation of filamentation in corona of spherical targets. Similarity parameters and approximative formulae for the maximum growth of filaments are deduced from numerical results.

- 80 - ECLIM18: P-l-23

HYDRODYNAMICS AND RADIATION PHYSICS OF LASER-IRRADIATED PLANAR TARGETS L. Drska, J. Limpouch, J. Vondrasek Fac. Nucl. Sci., Tech. Univ. of Prague

Radiation hydrodynamics of laser-irradiated foils is studied numerically in the frequency-averaged multigroup new diffusion approximation. A detailed model of inverse bremsstrahlung and resonance absorption and reflection of laser radiation is incorporated. Atomic physics packages used with the code include unified description of medium-Z and high-Z ion physics, EOS and radiation characteristics . Results of the simulation for aluminum indicate existence of two modes in the behaviour of the non-ablated part of the target: (1) The regime determined by the shock wave generated as a result of the ablation process. (2) The mode characterised by the radiation-driven thermal wave. Code and actual 2 experimental results compare quite closely . The rear surface measurements allow to study characteristics of non-ideal plasmas produced in the 3 first regime . The possibility to determine experimentally high-frequency electron conductivity of the plasma using the density gradient estimated from the difference of reflectivity of s- and p-polarized probing beam is analyzed.

1. L. Drska, J. Vondrasek: 6th Int. Conf. of High-Power Particle Beams, Kobe 1986, Paper P-A-10. 2. R. Arendzikowski et al.: 18th European Conf. on Laser Interaction with Matter, Prague 1987, Paper 0-2-2. 3. A. Ng, D. Parfeniuk, L. Da Silva, P. Colliers: Laser and Particle Beams 4, 555 (1986).

- 81 - ECLIM18: P-l-24

COMPUTER ALGEBRA APPLICATIONS TO THE PHYSICS OF HIGH-PARAMETER PLASMAS L. Drska, R. Liska Fac. Nucl. Sci., Tech. Univ. of Prague

Computer physics represents a powerfull tool of contemporary physics. Computer algebra, i.e. performing analytic computations on computers, is more and more applied in computational plasma and radiation physics. Three applications of computer algebra system REDUCE are presented. The first one is the computation of collision terms appearing as the six-dimensiopol integrals in the plasma fluid equations derived from the Fokker-Planck equation. The collision terms are analytically derived in full 13-moment approximation, without any other additional limitations used. These computations require treating of thousends individual terms and can never be performed by hand. The second application represents the program capable to determine accuracy, consistency and conditions for stability of a finite difference algorithm for solving restricted types of partial differential equations. (PDEs) . The third applications is the project for supporting design of numerical programs for solving systems of PDEs used in high-parameter-plasma physics. At present, the project contains the program for transforming PDEs into any nonorthogonal coordinates and the program for discretizing the PDEs by the integro-interpolation method.

- 82 - ECLIM18: P-l-25

X-RAY CHARACTERISTICS OF LASER-PRODUCED PLASMA A.V. Vinogradov, V.N. Shlyaptsev P.N. Lebedev Physical Institute, USSR Academy of Sciences, Moscow, USSR

There are a lot of problems that need investigation of X-ray emission of high-Z laser plasma. They are diagnostics of laser plasma dynamics and energy transfer, the use of laser heated plasma as an X-ray source etc. In all these problems X-ray emission play an important role, since X-rays of 0.1-10 keV region give the main contribution to plasma radiation losses. In this paper we investigate absolute X-ray yield of laser heated plasma. The gasdynamical, atomic and radiational processes are treated simultaneously in computer codes developed. One of the main goals was to include the possibility of investigation of heavy multicharged ions. Therefore particular attension was paid to correct treatment of ionization kinetics as well as line radiation, that gives the main part of plasma emitted energy /I/. The basic formulae used for numerical calculations are given. Gasdynamical and ionization processes are considered in accordance with /2/, radiative ones - - in accordance with paper /I/. The main limitations of the model and the fields of its application are also discussed. The results of calculation of transformation coefficient of laser emission into X-rays are presented. The "classical" and flux-limited electron heat transport are considered. The comparison with experimental and theoretical results of other Authors is given.

1. A.V. Vinogradov, V.N. Shlyaptsev, Preprint FIAN N 116, N 117, 1984 (In Russian). 2O A.V. Vinogradov, V.N. Shlyaptsev, Kvantovaya electronica, 1983, V. 10, N 3, Po509 (In Russian).

- 83 - ECLIM18: P-l-26

THE RADIATION FROM LASER PLASMA PLANE LAYER Yu.V.Afanasiev and K.A.Khachiyan P.N.Lebedev Phys.Inst.,USSR Acad.Sci., 117924 Moscow

The efficiency of converting the laser radiation into high-Z plasma emission under the interaction of the laser pulse and the condensed target is analyzed. The problem is complicated due to the ne- cessity of simultaneous consideration of unstable, hydrodynamic and thermal processes, and taking into account the kinetics of excitation, ionization and radiative plasma characteristics under different regimes of laser pulse interaction with matter. Using these estimates we have performed an optimization of the laser pulse parameters: ty (the flux density), v (duration), that is aimed at effective conversion.

As is shown analytically* under the developed in nz T hydrodynamics ( f = 10 - 10 ^ W/Cin2; tr£ 10" s) the relative fraction of the radiative losses are significantly lower. This is caused by a relatively low density of the produced plasma and high velocity of its expansion. At pulse duration V shorter than the time of plasma thermal confinement( V ~ 10^- 10'2 s; Z » 1, T ~ 1 keV) the laser pulse conversion into the plasma radiation can reach tens percent.

- 84 - ECLIM18: P-l-27

IONIZATION EQUILIBRIUM FOR HIGH-ZLASER PRODUCED PLASMAS

J.Farny, E.iVoryna

Institute of Plasma Physics and Laser Microfusion 00-908 -Varsav;. p.o.box 49, POLAND

A simplified non-LTE model was used to calculations of the ionization equilibrium in Al, Cu, Mo, Ho.Ag, Au and Uranium plasmas. Calculations were performed under assumption of constant critical electron densities forA ,= 1.06,0.53 and 1.25 pm. As a result of these simplified calculations a simple aproximation formula was obtained v/hich allows to estimate the meam charge number of ions function o electron temperature.

- 85 - ECLIM18: P-l-28

NONEQUILIBRIUfii EMISSION FROM THE LASER TARGET PLASMA B.N.Bazylev, F.N.Borovik, G.A.Vergunova, S.I.Kas1- kova, V.B.Rozanov, G.S.Romanov, L.K.Stanchits , K.L.Stepanov, A.V.Teterev P.N.Lebedev Physical Institute, Academy of Sciences of the USSR, Leninsky pr. 53, 117924 Moscow, USSR

Radiation characteristics of laser targets are studied in the soft X-ray region where photorecombi- nation, bremsstrahlung and transitions in the discrete spectrum are the basic mechanisms of spectrum formation. The impact-radiational model is employed to describe the states of the laser target plasma. Characteristics obtained fron the solution of the kinetic problem are used to compute absorption and emission coefficients. For setting time instants at the given field of gas-dynamic para - meters the transfer equation is solved and the do- tailed information is obtained on the spectral composition of the outgoing radiation and its temporal evolution. Effective emission temperatures and radiation losses are determined. Integral radiation parameters are compared v/hich have been derived from the solution of the transfer equation and employing the volume luminescence approximation. 1. B.N.Bazylev, P.N.Borovik, G.A.Vergunova et al. Kvantovaya Slektronika, v.13, II 10, p.1981 - 1990 (1986).

- 86 - ECLIM18: P-l-29

LINE RADIATION TRANSFER IN NON-EQUILIBRIUM LASER PLASMA S.I. Kaskova, G.S. Romanov, K.L. Stepanov Research Institute of Applied Phys. Problems, Minsk The self-radiation characteristics of plasma created under the effect of a powerful laser radiation on a target are considered. The radiation in the spectral range from 1 to 1300 ft is calculated in coherent assum ption for given gas-dynamic fields corresponding to various phases of laser target explosion. The source function was determined in accordance with a plasma radiation-collision model with the assumption of its transparency /1-2/. Calculations show that the contribution of line radiation to the total flux may be from 20 to 60 %. Mainly, this paper considers line radiation transfer. The effect of self-radiation on level populations and frequency redistribution at resonance scattering is taken into account /3/. The resonance scattering is predominant in the coronal plasma. Exit of photons from deeper layers of the target in comparison with the coherent case increases. Macroscopic plasma motion leading to spectral line shift is taken into consideration in the calculations. Output radiation spectral intensity distribution in oxygen and silicon H-like ions resonance lines has been determined. Spectral line profiles calculated with account of basic broadening mechanisms were used.

1. B.N. Bazylev, P.N. Borovik et al. Quant. Electr. v.13,p.1981, (1986) 2. V.I. Derjiev et al."Radiation of ions in non-equilibrium dense plasma",Moscow, (1986) 3. D. Mihalas. "Stellar atmospheres", Moscow, (1982)

- 87 - ECLIM18: P-l-30

X-Ray emission from laser-heated sperical plasmas

D. Mostacci, J.P. Dinguirard , R. Morse

Univ. of Arizona. Tucson, Arizona 85271, USA

Univ. P.Sabatier, 118 route de Narbonne

31062 Toulouse Cedex, France

We present calculations on the transport and emission of X-rays from a spherical

plasma created by laser heatinc of a spherical target. To deal with the the problem

of transfer of lisht through a plasma we adopt an apporoach whose novelty resides

in three points which we will call self consistency, Doppler effect and impact parameter croups. First we take a "dynamic" point of view to follow the mutual adjustement of level populations and light intensity till their final equilibrium value. Then we use a multi-frequency croup numerical method that makes it possible to include Doppler shift from flow in these calculations. Finally we have dealt with the angular croups of rays with a different perspective. We follow a number of rays, each one representative of a croup characterized by its distance of closest approach to the center of the sphere, in its path through the plasma.

The model is presented and discussed. The results are compared to experimental data.

- 88 - ECLIM18: P-1-

NUMERICAL SIMULATION OF THE X-RAY ENERGETICS IN SPHERICAL PLASMA.

J.P. DINGUIRARD, D. MOSTACCI. J. BRIAND, A. GOMES. J.C. KIEFFER. Y. QUEMENER, C. ARNAS, L. BERGE. M. ARMENGAUD.

C.P.A.T. Univ. P. Sabatier. CNRS-U.A 277. 118 route de Narbonne. 31062 TOULOUSE-CEDEX. FRANCE.

The x-ray emission of the outtr shell of an ICF spherical target, has been numerically studied at short laser wavelenght using a simple approximation based on recent experimental results. The influence of 1 keV shell emission on the core temperature is evalusted assuming the LTE and a negligible suprathermal electron preheat. The shell emissivity is close to a Planck function for a limited spectral range, the radiation temperature is laser energy dependent. The numerical simulation has been tested for different target configuration, the results are presented tor Si shell targets filled with Neon. The effect of this preheating can be es important as 40* in certa i n cases.

- 89 - ECLIM18: P-l-52

MODEL CALCULATIONS OF XDV GAIN IN LITHIUM-LIKE IONS FROM RECOMBINING LASER-PRODUCED ALUMINIUM PLASMAS

A. Klisnick, H. Guennou, A. Sureau, J. Virmont^ * L.S.A.I., Orsay, France and GRECO "International Laser-Matiere", Palaiseau, France (+) P.M.I., Palaiseau, France and GRECO "Interaction Laser-Matiere", Palaiseau, France.

In relation with the experiments developed at Palaiseau (1), we present a modelling study of population inversions and XI)V gain in Li-like aluminium (Al10+). We use a ID-hydrodynamical code FILM (2) postprocessed with a collisional radiative model POPNIV (3) for the excited levels of Al . Gain for 3-4 and 3-5 transitions is shown to occur in the corona of the plasma after the laser pulse, that is in the cooling phase of the expanding plasma. This is in good agreement with the experimental measurements of gain (1). Calculations are performed for several conditions of incident laser irradiation (pulse duration, energy flux, wavelength). A set of optimal plasma values (electron density and temperature, relative abundances of He-like and Li-like) is derived. The role of rapid cooling of the plasma together with "frozen ionization" is emphasized.

1. P. Jaegl£, A. Carillon, A. Klisnick, G. Jamelot, H. Guennou and A. Sureau ; Europhys. Lett. 1_ (1986) 555. 2. J.C. Gauthier, J.P. Geindre, N. Granjouan and J. Virmont ; J. Phys. D, Ib (1983) 321. 3. H. Guennou ; Thesis Orsay (1983).

- 90 - ECLIM18: P-l-33

Electronic Structure of Matter at High Compression; Transition to Fermi-Gas Behaviour J. Meyer-ter-Vehn, W. Zittel Max-Planck-Institut fiir Quantenoptik D-8046 Garching, FRG

The electronic structure and the equation-of-state (EOS) of cold matter at high compression has been studied systematically for a number of materials, by performing ab initio band structure calculations based on the augmented-spherical-wave (ASW) method3-> and by comparing these results with the quantum-statistical-model (QSM) which is the Thomas-Fermi model with exchange and gradient corrections treated self-consistently. The main focus of this work is on the effect of atomic shell structure which is expected to produce non-mono- tonic behaviour in the cold EOS (pressure vs. density) in comparison to the smooth behaviour of the statistical model. A major result of this work is that pressure ionisation, i.e. squeezing of bound states into the continuum due to high pressure, does not produce any remarkable EOS irregularity in all cases studied, in contrast to the predictions of Kirzhnits. However, EOS irregularities do appear systematically due to pressure-induced shifts of valence bands against each other. As a rule, electrons are redistributed from bands of low angular momentum (typically s-state) into bands of higher angular momenta (typicallyp-and d-states). These isostruc- tural transitions tend to relax the pressure and lead to regions of EOS softening. These irregularities are particularly pronounced for alkali metals, and new explicit results are given for Li2 and K3. Results for He, Be, and Al are also shown.

1. A.R. Williams, J. Kiibler, CD. Gelatt, Phys. Rev. B19 6094 (1979). 2. W. Zittel, J. Meyer-ter-Vehn, J. Kubler, Physica 139B 364 (1979). 3. W. Zittel, J. Meyer-ter-Vehn, J. Kubler, to appear in Sol. Stat. Comm. (1987).

This work was supported in part by the Bundesministeriura fiir Forschung und Technologie.

- 91 - ECLIM18: P-l-34

Planck and Rosseland mean Opacities of high-Z Plasmas"1"

G.D. TSAKIRIS AND K. ElDMANN Max-Planck-Institut fur Quantenoptik D-8046 Garching, Fed. Rep. of Germany

A method is described for computing the Rosseland and Planck mean opacity of any element as function of temperature and density. The method is based on the "Average Ion" representation for calculating the occupation numbers of the various electronic levels. The photoabsorption coefficients are calculated in the hydrogenic approximation. To account for the important contribution of line absorption a simple phenomenological method has been developed which takes into consideration effects like the broadening of the upper electronic levels into bands and the band overlapping in the heaviest of elements . Calculations are presented for various elements and compared with more accurate results. Power-law scaling relations for the Rosseland and Planck mean opacity dependence on temperature and density are derived for a number of elements of practical importance.

+ This work was supported in part by the Commission of th* European Communities in the framework of the Association Euratom/IPP.

_ 92 - ECLIM18: P-l-35 RADIATION HEAT WAVE Pfc:'! F ' - .IT I: N 'JN COLD MATTER

R . Ramis

E . T . S . I . A e i- o n a u ; 1 L. us, Insti tuto de Fusion Nuclear, Universidad Pclitecnica df Madrid, 28040-Madrid, Spain

When a large amount of e.iergy is dumped on a localized region of a high a t. r;r: i >r -numbe r material, the thermal flux, due essential iy to radiation, heats the adjacent colder regions. Simultaneously to this process the huge pressure gradients cause motion of the matter jl| |2|. We consider sn optically thick medium where the heat radiation flux is proportional to the temperature gradient. Usually r.h(- proportion heat conductivity ic is strongly dependent en the temperature (i.e. for a total ionization ic % T ^ -*'' ^ i 3 | ) . We assume icuTn , being n a large number, and expand all variables as asymptotic sequences of powers of the small parameter e H 1 / n . The regime of the solution (neat wave versus a combination of ablation and shock waves) is found to depend on the T /(C Tp C adimensional parameter B-f

• 1. W.C. Mead, et al., Physical Review Letters 4 7, 1289 (1981 ) . 2. T. Yabe, and C. Yamanaka, Comments Plasma Phys. Con- trolled Fusion, 9, 169 (1985). 3. Ya.B. Zeldovich and Yu.P. Raizer, Physics of Shock Waves and High Temperatures Hydrodynamic Phenomena. 4. A. Barrero and J.R. Sanmartin, Phys. Fluids 20, 1155 (1977) . b. J. ivleyer-ter-Vehn, et al., Physics Letters 2.2£ • 410 ( 1984 ) .

- 93 - ECLIM18: P-l-36

CRYSTAL X-RAY ACCELERATOR T. Tajima Department of Physics and Institute for Fusion Studies The University of Texas at Austin, Austin, Texas 78712 M. Cavenago Scuola Normale Superiore Pisa, Italy

An ultimate linac structure is realized by an appropriate crystal lattice (su- perlattice) that serves as a "soft" irised waveguide for X-rays. High energy (~ 40 keV) X-rays are injected into the crystal at the Bragg angle with peak power > 3 x 109TV to cause the Bormann anomalous transmission, yielding the slow wave accelerating fields. Particles (e.g., muons) are channeled along the crystal axis. Because of channeling by the crystal structure the particle beams are very well collimated, leading to very high luminosity and brightness: the cross-section* of the beam is much less than A

- 94 - ECLIM18: P-l-37

'i'iiiJ /iLTii'HATlC-i: O^1 CHARGED PARTICLE JNiRGY IN PLASMA UEDiL'H Tri:-; AUTIOli OF A STRONG EXTERNAL ELECTROMAGNETIC FIELD rJ.A. Aeo;;ian, G.G. I.'Iatevossian Institute of Rodiophysics and Electronics Academy of Sciences of the Armenian SSR, Ashtarak-2, Armenian SSR, USSR. Trie influence of a powerful external electromagnetic field upon the plasma brings to alteration of its dispersion characteristics. In consequence of this the fast charged particle, moving in plasma,ra- diates longitudinal waves not only on plasma frequency i*Jp , but also on combination frequencis tncOof^p (n is a whole number, CJO- the frequency of the external field) [1], In spite of this the wave vectors and amplitudes, radiating by a charged particle, are proved to be depending on parameters of the external field and in this sense are controllable values. Be- couse oC this the alteration of charged particle energy for longitudinal waves radiating is also proved to be depending on the parameters of the external field. As the analysis shows, the losses of fast particle energy for radiating the waves on the frequency $_Wp are oscillating when the pararcoter C Ec cJp/ffiU U)6 is alterating (where Eo is the amplitude of the external field; u - the speed of the particle translation motion; e,:n - the charge and the mass of electron respectively) and may take zero value when this parameter takes the values, corresponding tozeros of the Besoel function of zero order. In spite of this the charged particle energy losses for longitudinal waves radiating with frequencisflcOo+-tJp may be found positive. The obtained result is confirmed with numerical computation [2]. The oscillation of a charged particle and plasma electrons under the action of a strong external field bring also to dependance of the fast charged particle losses on its charge polarity on account of that posi- tively and negatively charged particles are vibrating opposite in phase or in phase with the plasma electrons [;>]. 1. K).M. Ajiwen, Jl.lL PopiyHOB, P.P. PaMa3aniBH.'iH, £3T$, 61, 1477 (T97I). 2. 37A. AKorwH, r. T. MaTeBOCHH, <$w3HKa nvia3MH, 10, 648 (1984). 3. 3.A. AKonnH, T.T. MaTeBOCHii, M3B. BY3:OB "PaflHO$H- 3HKa", 26, 1310 (1983).

- 95 - ECLIM18: P-l-38 SLOWING DOWN OE IONS BY IDEAL PLASMA WITH ARBITRARY DEGENERACY D.V. II'in, A*A. Levkovsky, V.£. Sherman, O,B. Vygovskyo Zavod-VTUZ, 195108, Leningrad, USSR. The stopping power "^P and range A of heavy charged particles with mass M are calculated by means of Coulomb logarithm approximation. Expressions obtained are valid for arbitrary parameters %,|£? »Hs,^~ characteristic velocity of plasma electrons) wxth an accuracy of mc/M • It is shown that with an accuracy to a scaledB/dte. as a function of M'TT/i'i is determined by chemical activity 2=<*pCh/tif) O4- chemical potential) only, and not by plasma density p and temperature T* Moreover, one can choose the scale value of a characteristic velocity Vc in such a way that the expression for 'B), where the dependency on is essential only byy~i). An analytical approximation is received for this one-parameter family* The scaling range-energy dependency \/ho-%(£/£o) is obtained on the basis o£dlF/clt. This one-parameter family of curves describes the ranges of heavy charged particles in plasma with arbitrary composition and conditions* Tbe scales of ranges Ao and energies Eo are easily defined by plasma parameters*

- 96 - ECLIM18; P-l-39

THEORY OF THE PEAKED REGIMES IN COMPRESSED MEDIA N.V. Zmitrenko, S.P. Kurdyumov, A.P. Mikhailov Keldysh Institute of Applied Mathematics USSR Academy of Sciences, Moscow, USSR

Studying the high, values of pressure and density of a matter that can be achieved with minimal energy and laws of optimal (unshocked) compression immediately leads to an investigation of peaked regimes C13* Namely, the gas compression by a piston without any shock waves can "be reached only if a pressure at the piston increases more rapidly than behind a front of the cumulating shock wave, A general approach which was developed for investigation of the peaked regimes in based upon an analysis ot self-similar solutions with separation of variables fcfX't) - ^''{x>'sy'fj^j- »,. ^and solutions of the type Fj^^t) •=ftl'V{i?-t) )(tj -*)*' , ty<*> is the focusing time, JT and i? are the mass and time variables, Ft are desired functions. Such an approach allows considering a wide class of dissipative media with various thermophysical properties. The class of peaked regimes that lead to the localization of gas dynamic effects in a finite mass of a matter is distinguished and studied u21. The consideration of dissipative media leads to an investigation of the localization of thermal, gas dynamical, magnetic hydrodynamical and other processes, which is accompanied by an appearance of structures differing by physical nature in a compressed mattert 3,42,

1. N.V. Zmitrenko, S.P. Kurdyumov, Appl. Mech. and Techn. Phys., 1977, N 1, p.>23. 2* N.V» Zmitrenko, S.P. Kurdyumov, A.P» Mikhailov, - In: Modern Mathenu Problems, v»29t Moscow, VINITI, 1986. 3. M.A. Demidov, A.P. Mikailov, Appl. Matenu and Mech., 1986, v.50, N 1, p.119-127. 4. N.V. Zmxtrenko, S.P. Kurdyumov. - In: Laser Fusion Problems, Moscow, Atomizdat, 1976, p.279-294.

- 97 - i 8 :

NEW SYNERGETIO PROPERTIES OP DIFFUSION PROCESSES IN PLASMA

+ 6.G. Elenin*, K.V0 Zmitrenko , S.P. Kurdyumov*, E.S. Kurkina*,.A.P. Mikhailov , A.B. Potapov , A.A. Samarskii +Keldysh Institute of Applied Mathematics USSR Academy of Sciences, Moscow, USSR

*Moscow State University, Moscow, USSR An investigation of the heat production and propagation processes in a nonlinear media turns out to be immediately connected with studying the effects of inertial behavior of the temperature profiles, origin of peaked regimes in a medium and appearance of loca- lizated dissipative structures Cil. For the quasilinear (electron) heat conductivity equation the classes of initial temperature profiles are shown, which are localized in a certain domain on a finite time interval. The conditions are found out when the matter temperature increases at the peaked regime in a heat conducting medium with a heat source is localized in a finite region.She solutions of such type sometimes represent a "spectrum" of localized thermal structures L2 3. In a multidimensional case a shape of the localization domain is an important element for solutions of the equation ^ - J;v( Kcw^vu ) ^-<^u^^. in the two-dimensional case a method is proposed for construction of the space-ingomogeneous solutions, which is based on linearization of the equation in the localization region and on the use _of a "sewing" with asymptotics when i?| -> ^ L33c Two types of structures are obtained, which are invariant to a finite group of space symmetry. Thus the organization forms of a continuous dissipative medium are determined, their architecture depending on the medium parameters only £3» 41« 1. N.V# Zmitrenko, A.P. Mikhailov, "Inertia of heat", Moscow, Znanie, 1982. 2. A.A. Samarskii, G.G. Elenin, N.V. Zmitrenko, et al., Soviet Doklady Ac.Sci., 1977. v.237, N 6, p.1330-1333. 3» S.P. Kurdyumov, E.S. Kurkina, A.B. Potapov, A.A. Samarskii, J.Num. Mathetn. and Ma them. Phys., 1986, v.26, N 8. 4. S.P. Kurdyumov. - In: "Modern Problems of Mathema- tical Physics and Numerical Mathematics", Moscow, Nauka, 1982, p.217-243.

- 98 - ECLIM18: 1-2-1

INVITED PAPER

A. Caruso

Energy Research Center, ENEA, Frascati ECLIM18: 1-2-2

RECENT RESULTS OF INVESTIGATIONS OF THE LASER INTER- ACTION WITH MATTER AT THE IPPLM

S.Denus

Institute of Plasma Physics and laser Microfusion, 00-908 '.Varsaw.p.box 49, POLAND

A summary of recent experimental and theoretical investigations of the laser matter interaction and the plasma compression carried out at the IPPL". is presented in this paper. Ths four beam Nd-glass laser, was used in the plasma compression exoeriment. For the study of physical processes in the laser produced plasma one beam Nd-glass and COp lasers were employed.

- 100 - ECLIM18: 1-2-3

18th ECLIM, Prague, May 4-8,1987

Pulsation of co and 2co Emission from Nd Laser-Produced Plasmas

R. Dragila, B. Luther-Davies and A. Maddever

Laser Physics Centre, Research School of Physical Sciences, Australian National University, P.O.Box 4, Canberra, ACT 2601, Australia

Both 2co and lco emission from plasmas generated by 60 - 400 psec 1 urn Nd lasei radiation at intensities above 1014 W/cm2 has been found to pulsate with average burst length « 10 psec. The emission is localized in small regions = 5 urn in diameter with their position and intensity varying randomly from shot to shot. The influence of the temporal modulation on the spectra of the emitted light and possible mechanisms leading to this behaviour will be discussed.

- 101 - ECLIM18: 1-2-4

GAIN AND RADIATION TRAPPING FOR LONG-LASER-PULSE PRODUCED PLASMA

W. Brunner, Th. Schlegel

Zentralinstiti.it f-uer Optik und Spektroskopie der Akademie der Wi ssenschaften der DDR, Rudower ChausseE? 6, DDR-1199 Berlin, GDR

Recently, the inversion condition for laser-produced plasmas was analysed theoretically -for -fibre targets in relation to the intrinsic intensity of heating long laser pulses (ti_ = 10 ns) El 3. It was shown, that an inversion and therefore a gain will be reached after the laser pulse (to»±n > 10 ns) for a relatively long time ( ta«lr, 5 to 10 ns) . This theoretical result seems, in principle, to be in agreement with experimental findings C23. Especially, it was shown - taking into account hydrogen like carbon ions and laser intensities near iO13 W/cm3 - that the gain for the 4—>3 transition is small << 0.05 cm"1), but will be extendet over a wide spatial region (1OOO to 4000 • um) and a long time duration. The influence of radiation trapping is, as known, small in contrast to the 3~>2 transition. The gain for this transition in optically thin plasmas is < 5 cm"1, restricted to a small spatial region (near 1000 /um for 10 ns laser pulse) and will be drastically reduced for optically thick plasmas caused by the reabsorption of the L«x- line. However, for plasmas generated by long laser pulses the ionisation degree strongly depends on time and the distance from the target and we will show that especially the occupation of the hydrogen like ground level and, therefore, the influence of the reabsorption may be relatively small in definite time and spatial regions. This result will be discussed in more detail.

C13 W.Brunner and Th.Schlegel -J.de Physique 47 (1986) C6-99

C23 P.Jaegle, A.Carillon, A.Klisnick, G.Jamelot, H.Guennou, and A.Sureau -Europhys. Lett.i (1986) 555

- 102 - ECLIM18: 1-2-5 EXPERIMENTAL STUDIES ON LASER IRRADIATED THIN FOIL TARGETS H.C. Pant Bhabha Atomic Research Centre, Bombay

- 103 - ECLIM18: 1-2-6 RADIATION TRANSPORT IN LASER-TARGET INTERACTIONS A. Ng The University of British Columbia

- 104 - ECLIM18: 0-2-1

Simulation of Laser-Plasma Interactions with Atomic and Radiation Effects

R. Marchand, C.E. Capjack, Y.T. Leea, and R. Fedosejevs Department of Electrical Engineering University of Alberta Edmonton, Alberta T6G 2G7 Canada

A one-dimensional Lagrangian code is used to model the interaction of laser light with plasma. The equation of state used is a realistic, piecewise analytic fit, which allows simulation starting from normal conditions. The atomic physics required in the code (ionization, radiation rate, and opacities) is computed from tables generated using a non-LTE hydrogenic atom model. Radiation transport is treated approximately using a new, numerically efficient recursive algorithm. The code is used to model recent experiments done with planar Al, Ti, and Fe targets. The code predictions are compared to experinental results, in particular, with regard to the mass ablation rate, and the X-ray conversion efficiency.

Lawrence Livermore National Laboratory, University of California, Livermore, CA 94550, USA.

- 105 - ECLIM18: 0-2-2

ENERGY TRANSPORT THROUGH THIN ALUMINIUM FOIL IN LASER-TARGET EXPERIMENT R. Arendzikowski, S. Denus, J. Farny, H. Fiedorowicz, K. Jeziak, W. Mroz, S. Nagraba, W. Pawlowicz, A. Wilczynski, J. Wolowski IPPLM, Warsaw P. Bitzan, L. Drska, J. Limpouch, G. Loncar, L. Plna, J. Vondrasek Fac. Nucl. Sci., Tech. Univ. of Prague

Energy transport throught thin Al foils irradiated with 1.06 urn, 1 ns laser pulse at intensities 10 " W/cm was investigated. The diagnostic setup used in the experiment allowed to estimate the plasma temperatures using ion collectors measurements, method of filters of different thicknesses and X-ray spectroscopy. The luminous radiation emitted by the back surface was studied by the use of optical spectroscopy. Time dependence of plasma density profiles and velocity of nonablated part of the target were measured with the set of interferometric and shadowgraphy diagnostics. Experimental results were compared with one dimentional radiation-hydrodynamic simulations. It was shown that radiatively driven heat wave play an important role in the energy transport processes through thin Al foil.

- 106 - ECLIM18: 0-2-3

STIMULATED RAMAN SCATTERING IN LONG SCALELENGTH PRE-FORMED PLASMAS

A. Giulietti**, O. Wllli, J.S., Karttunen •••, O. Bassett, M. Gr, N. Islava

Imperial College of Science and Technology, Prince Consort Road, SW7 2BZ, London, UK

* Rutherford and Appleton Laboratory, Didcot, UK ** Istituto di Fisica Atomica e Molecolare, Pisa, Italy *** Technical Research Center, Helsinki, Finland

Four beams of the RAL Vulcan laser facility have been used in the "line focus" configuration to produce a plasma of 1 mm length from thin foil Al and Au targets. Temperature and density decreased during the hydrodynamic expansion and covered an interesting range of values. A high power, green, interaction beam was focused into the performed plasma along the main axis up to irradiance of 1015 W/cm2. Time integrated and time resolved backscattered Raman spectra were obtained with different delays in respect to the heating pulse. The experimental data showed several novel features which are consistent with theoretical predictions. Moreover SRS seems to be influenced by self-focusing of the interaction beam, as also confirmed from Brillouin and Interferometry data.

- 107 - ECLIHiS:

Experimental study of the filamentation instability

in short wavelength laser produced plasmas

C. Arnas, J. Briand. J.C. Kieffer. A. Gomes. J.P. Dinguirard

V. Quemener, L. Berge, M. Annencaud

Universite P. Sabatier. CPAT. DA 277 du OiRS

118 Route dc Narbome. 31062 Toulouse-Cedex. France

and GRECO ILM, Ecole Polytechnique, 91128 Palaiseau. France.

We present a comprehensive set of experimental results on the periodic structures

which are observed by X ray imaging (1 kev range) in short wavelength laser

produced plasmas. The behavior of the observed Hibernation structures produced by the developnent of the filaaentation instability is studied for laser irradianoe

IX between 10 ' Vym /a? and 10* Wyro ,cm2, for 1 ym, 0^3 ym and 03 ym laser wave lengths, for low Z (CH) and medium Z (Al) targets, for incidence angles (0", 30*, 45") and for various target geometries, for the periodicity of the filamentation are presented. The experimental data are interpreted by means of a simple theoretical model of the filamentation instability, which takes into account the finite length of the ptemw. The of the ponderonotive filanentatkm in the range of our parameters is attested.

- 108 - ECL1M38: 0-2-

STUDY OF LI-LIKE IONS IN LASER-PEODUCED PLASMAS, POt X-Uf LASERS RESEARCH H. Guennou, A. Sureau, C. MSller Laboratoire de Spectroscopie Atomique et University Paris-Sud - 91495 ORSAY (PRANCE)

Laser-produced plasraas are known as media where population inversions between excited levels of ions can occur, particularly during the recombination phase. In the case of lithium-like ions, both experimental result* and theoretical predictions have been developped for Al*°* /1-3/. It appears interesting to investigate other lithium-like ions, as S13+ 131, and higher-Z elements. Here, 19+ we present the results of calculations concerning Tl and In this last case, the observation of a population inversion between the 3d and the 4f levels has been recently announced A/, the corresponding transition wavelength being 25.6 A. Our calculations show in which domains of density and temperature the population inversions can actually hold, and how large they can be according to the plasma hydrodynamics conditions. Comparisons with previous results on Al10+ and S13+ are presented.

/I/ P. Jaegle, G. Jamelot, A. Carillon and A. Klisnick J. Physique 42, C6-31 (1986) 111 A. Klisnick, H. Guennou and J. Virmont, J. Physique 47, C6-345 (1986) 131 H. Guennou, A. Sureau and C. M811er, J. Physique U]_f C-351 (1986) /4/ CM. Brown, J.O. Ekberg, U. Feldman, J.F. Seely, M.C. Richardson, F.J. Marshall and W.E. Behring, to be published (private communication).

- 109 - ECLIM18: 0-2-6

LASER-DRIVEN IMPLOSION STUDES L'cJING THE SOFT X-RAY EMISSION MEASUREMENTS

S.D-snus, H. Fiedorowice, K.Oeziak, P.Parys /.V.Paiviov.icz

Institute of Plasma Physics and Laser Microfusion - 00-908 Warsaw, p.o.box 49. POLAND

Ths mass ablation rate and ablation pressure on laser-irradiated soherical glass microsnells were measured using the soace-resolved soft IC-ray spectro- scoDy and time-resolved soft X-ray emission measurements. Four beam Nd-glass laser was used for the niicrotarcet irradiation. Some shells were coated with 1-3 jum nolystyrene and 0.01 .um Cu layers for burnthrough measurements. Ths X-ray emission fror. olasma was detected by fast semiconductor detectors and ADP crystal imaging soectrograph. The characteristic crescent-shaped X-ray spectral image forr.-.ed in the lines of the He-like ions is caused by Ooppler effect in spherically expanding plasma. The analysis of the X-ray spectra provided information about the expansion velocity of X-ray emitting region electron density in this region, mass ablation rate and ablation pressure. For layered shells the tamped expansion of Dlasma effect was observed.

- 110 - WEDNESDAY

MAY 6

)M\l\L ECLIM18: R-3-1

LASER-PLASMA EXPERIMENTS AT THE NOVA LASER FACILITY*

E. M. Campbell

Lawrence Livermore National Laboratory University Of California Livermore, Ca. 94550

ABSTRACT Recent experiments performed at the Nova laser facility covering a number of topics will be presented. Experiments include laser-plasma interaction physics in large plasmas, the dependence of x-ray conversion efficiency on intensity, laser wavelength, and temporal pulse history, high density, ablative implosions, hydrodynamics, and x-ray laser physics. Highlights include the measurement of dense (p > 20 g/cc), hot (Ti > 1.5 keV) ablative implosions, high yield (> 1.8 x 1013) and improved fusion efficiency (nF > .25%) from non-isentropic, high temperature implosions, a quantitative understanding of stimulated Raman scattering in long scalelength plasmas, and observation of numerous transactions in the XUV region of the spectrum which gain > 1 cm" . The 2O6A and 209A lines of neon-like selenium have measured gain length products of > 15 and output power > 10 watts.

*Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore Laboratory under contract number W-7405-ENG-48.

- 113 - ECLIM18: R-3-2

Laser-Plasma-Interaction Experiments Using Multikilojoule Lasers Dr. R. Paul Drake ICF Program, Lawrence Livermore National Laboratory Livermore, CA, USA 94550 A large number of experiments throughout the world have produced laser intensities, electron temperatures, and collision rates that are comparable to those anticipated in high-gain, laser-fusion reactors. In recent years, high-power lasers have become able to irradiate targets with more than one kilojoule of energy at powers above one terawatt. This development has made possible new types of laser-plasma-interaction experiments. In particular, one can use such lasers to produce gradients in the plasma that are much less steep than those produced previously. By irradiating solid targets, one can produce density-gradient scalelengths of several hundred laser wavelengths. By irradiating thin targets that burn through and expand, one can produce scalelengths larger than one thousand laser wavelengths. This significantly increases the gain or decreases the threshold for a large number of mechanisms that can scatter the laser light.

During the past few years, we have performed such experiments with lasers operating at wavelengths of 1.06, 0.53, 0.35, and 0.26 microns. These experiments typically used irradiating intensities of a few times 1015 W/cm2 and pulse durations of 1 ns. In all cases, we have at least some data from both thick and thin targets. We have seen evidence of several scattering mechanisms, including Raman sidescatter, Brillouin sidescatter, and efficient Raman backscatter. In addition, we have recently conducted an experiment with thin targets, in which we varied the laser intensity by more than two orders of magnitude while the density-gradient scalelengths changed much less. This experiment allowed us to explore the details of Raman scattering in more depth.

- 114 - ECLIM18: R-3-3

RECENT PROGRESS IN ICF AT LIVERMORE*

John D. Lindl Lawrence Livermore National Laboratory P. 0. Box 808/L-477 Livermore, California 94550 USA

ABSTRACT Progress within the past year has moved us much closer to demonstrating the scientific and technological requirements for laboratory fusion. This progress has been made possible by operating at the 3rd harmonic of ly light which virtually eliminates concern about hot electrons, by advances in diagnostics such as 100 ps x-ray framing cameras which greatly increase the data available from each experiment, by advances in material science such as high quality low density foams which make cryogenic targets much more feasible, and by advances in conceptual ICF reactors which for the first time make fusion power competitive with advanced fission and coal. Making use of many of these new capabilities, Nova operating at 20 kJ has achieved a major improvement in confinement conditions for ICF implosions. We have achieved values of rtxQ of mid 1O'4, in close agreement with computer calculations. We will present these results as well as examples of advances in several other areas and discuss the implications for the future of ICF with lasers and heavy ion beam drivers.

*Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48.

- 115 - ECLIM18: R-3-4

PHYSICAL PROPERTIES OF SUPER-DENSE PLASMA AND NUMERICAL MODELING OF PULSED PROCESSES AT HIGH ENERGY CONCENTRATIONS V.E. Fortov Inst. of Chemical Physics, Acad. Sci. USSR

- 116 - ECLIM18: P-2-1 RESONANCE ABSORPTION WITH SELF-CONSISTENT PROFILE MODIFICATION

E. Ahedo and J.R. Sanmartin

E.T.S.I .Aeronauticos, Universidad Politecnica de Madrid 28040-Madrid, Spain

Resonance absorption of laser light in the stratified plasma ejected by a target when irradiated by the light is analysed. Profile modification within a thin layer due to the radiation pressure tensor with thermal wave effects, but no collisions, are considered. For a large incidence angle 6 and low light intensity there is no resonance; the maximum magnetic field occurs at a sonic point that takes into account the radiation pressure. For small e or high intensity, there is a sublayer, sustaining the plasma wave, embedded in the main layer; quasineutrality may not hold there. The fractional absorption is determined.

References

1. Lee K., Forslund D.W., Kindel J.M. and Lindman E.L. (1977), Physics Fluids 20, 51; Sanmartin J.R. and Mon- tanes J.L. (1980), Physics Fluids 23, 2413. 2. Takabe H. and Mulser P. (1982), Physics Fluids 25_, 2304. 3. Kruer W.L. (1982), Physics Fluids 25, 2324.

- 117 - ECLIM18: P-2-2

MODULATIONAL INSTABILITY IN THE BEAT WAVE EXPERIMENTS

o h 3 *} f D. Pesme , S. Karttunen , G. Laval , N. Sylvestre , and R. Salomaa

a. Centre de Physique Theorique, Ecole Polytechnique, 91128 Palaiseau-Cedex, France. b. Technical Research Centre of Finland, P.O.B. 169, SF-00181 Helsinki 18, Finland. c. Helsinki University of Technology, Department of Technical Physics, SF-02150 ESPOO, Finland.

The coupling of a plasma wave to the ion acoustic waves may result in a decay or a modulational instability. This problem is investigated in the context of beat wave experiments. An upper limit for the lasers pulse length is given, above which the plasma wave becomes incoherent before reaching the maximum amplitude allowed by the nonlinear relativistic frequency shift.

- 118 - ECLIM18: P-2-3

SIMPLE MODELS OP HOT ELECTRON GENERATION IN LASER PLASMA V.B.Rozanov, S.A.Shumsky P.N.Lebedev Physical Institute, Academy of Sciences of the USSR, Leninsky pr. 53, 117924 Moscow, USSR

The leading mechanisms of hot electron generation in modern laser-plasma interaction experiments are under consideration. Approximations dealing with severe destortion of electron distribution function are discussed. Theoretical scaling of resonant hot electron temperature versus laser intensity and wavelength is obtained. The effects of multiple hot electron interactions with resonant fields, that can be important in the experiments with thin shell targets, in the presence of sufficiently large magnetic fields and under illumination of a target by a multi-line laser radiation are investigated. It is shown , that in the latter case hot electron spectrum has an advantage over the usually observed one when the monochromatic light is used, due to the absence of hard tail. This makes the multimode lasers promising drivers for LTP.

- 119 - ECLIM18: P-2-4 DYNAMJCAL STRUCTURE FACTOR OF A PLASMA IN TERMS OF TRANSPORT COEFFICIENTS

I.Deha*

Istituto di Fisica Atomica e MoLecolare Via del Giardino,7 56100 PISA Italy * Permanent Address: Universite des Sciences et de La Technologie Houari Boumedienne BP.31 EL Alia, Bab Ezzouar, ALGER, Algeria

The method of retarded and advanced Green's functions used by Bogo Lyubov( J r) et al.d) to obtain the dynamical structure factor of a simple neutral Liquid is applied in the case of a fully ionized hydrogen plasma. The plasma is described by the hydrodynamic equations coupled with Maxwell's equations for self-consistent fields. The study of the reaction of such a plasma to an infinitesimal periodic perturbation of its Hamiltonian gives us two expressions for the dynamical structure factor in terms of the transport coefficients. The first one is obtained using a one-fluid description when ions are at rest and act only as neutralizing background, the second expression incorporates the ions motion. The results are compared with those from other methods.

1. N.N. Bogolybov(Jr), V.V. Kamaeva, V.N. Ptechko Teor. Mat. Fiz. Vol. 32,59(1977)

- 120 - ECLIM18; P-2-5

RELAXATION OP QUANTUM SYSTEMS IN STRONG ELECTROMAGNETIC FIELD - NEW NONLINEAR EFFECTS E. G. Pestov P.N.Lebedev Physical Institute, USSR Academy of Sciences, Moscow, Leninsky prospect 53

The strong electromagnetic field (EMF) has a substantial influence on the relaxation of quantum systems (QS) in the interaction with a thermostat and electromagnetic vacuum* The relaxation parameters become dependent on the intensity of the external EMF, Besides, the relaxation scheme changes, namely, there appears a new correlation between the density matrix elements in the quantum system, which is absent in a standard Bloch equation. This correlation is proportional to SMF amplitude, or intensity. We treated this fact in /1/, /2/ in frames of the atomic collisions theory, where we predicted the effect of the field narrowing of spectral lines in the radiation of gaseous atoms in strong resonant EMF. The dependence of the "thermostat11 relaxation parameters on the EMF intensity has been investigated most thoroughly. However, the variation of the spontaneous relaxation characteristics under the action of the strong resonant EMF has been still insufficiently studied /3/. We consider in detail the spontaneous and "thermostat" relaxation of the quantum systems in strong EMF, and some new nonlinear effects.

1. E.G.Pestov, S.G.Rautian. JETP, 64, 2032 (1973). 2. E.G.Pestov. JETP, 86, 1643 (19647. 3» E.G.Pestov. Kvantovaya Elektronika, 2A* W? O986)#

- 121 - ECLIM18: P-2-6

NON-UNIFORM IRRADIATION OF SPHERICAL LASER TARGETS

J. Sanz, J.R. Sanmartin, and J.A. Nicolas

E.T.S.I.Aeronauticos, Universidad Politecnica 28040-Madrid, Spain

The structure of the corona ejected by a laser-irradiated target under spherical symmetry conditions is well known (1-4). A weakly non-spherical irradiation is here considered and a linear analysis in terms of spherical harmonics is carried out. A magnetic field is generated so that steady Maxwell equations are coupled in, and general Braginskii terms must be used in the heat flux and the ion-electron friction; this results in Righi-Ledm- heating and electron entropy drift due to the electric current. The critical surface is carefully located. Under- dense refraction is taken into account. Complete results are given in terms of the three dimensionless parameters (Legendre index, critical to ablation radius ratio, and light wavelength to electron mean free path ratio).

References 1. Afanas'ev Yu.V., Gamalii E.G., Krokhin 0. and Rozanov V.B., Soviet Phys. JETP 44, 311 (1977). 2. Max C.E., McKee C.F. and Mead W.C., Physics Fluids 23, 1620 (1980). 3. Sanz, J., Lifian A., Rodriguez M. and Sanmartin J.R., Physics Fluids 24, 2098 (1981). 4. Nicolas J.A. and Sanmartin J.R., Plasma Physics and Controlled Fusion, 27, 279 (1985).

- 122 - ECLIM18: P-.:'-7

SHOCK EXPLOSION AND IMPLOSION, ANALYTICAL SOLUTIONS, APROXIMATIONS INVOLVED Eli A. Mishkin and Carlos Alejaldre Polytechnic Institute of New York

The mathematical models of shock explosion and implosion (2) and the approximations they involve are considered. Sedov s method fails in case of modern large explosions. It is also unreasonable to implode a large pellet of infinite dimensions. It shown that in case of implosion the method of the self-similar solution, i.e., a shock coming from infinity, introduces an error 10 %. The analysis of a hollow pellet is to be discussed.

L.I. Sedov, Similarity and Dimensional Methods in Mechanics, Academic Press, N. Y., N. Y. (1959). Yasuichi Fujimoto, Eli A. Mishkin and Carlos Alejaldre, Phys. Fluids, 2*3, 3018, October 1985, and references.

+Permanent address: Association Euroatom, Junta de Energia Nuclear, Madrid, Spain

- 123 - FJLAiWENTATiON Aris; iHWULATED BR1LLOUIN SCATTERING iH LONG SCAJ.EI.ENGHT PRE.-FGRMtD PLASMAS

A. Giufietti*, O. WH«f. J.S. Karttunen**, D. Bassett, N. Islava

Imperial College of L-:ienco and Technology, Prince Consort Road, SW7 232, London, UK

* Istituto di Fisica Atomica t; Mok-colare, Pisa, Italy ** Technical Research Center, Helsinki, Finland

Four beams of the RAL Vulcan laser facility have been used in the "line focus" configuration to produce a plasma of 1 mm iength from thin foil Al and Au targets. Temperatue and density decreased during the hydrodynamic expansion and covered an interesting range of values. A high power, green, interaction beam was focused into the pre-formed plasma along the main axis up to irradiance of 10^ W/cm^. Time integrated and time risolved backscattered Brillouin spectra were obtained with different delays and show clearly two different shifts for each event, the larger originating from hot spots in the laser beam produced by filamentation instability in the plasma. This filamentary structure was also confirmed from interferometry. The temperature into the hot spots and the rise time of the instability are estimated from Brillouin data.

_ 124 - ECL1M18: P-2-9

!k£eD s-.ent a| evidence of strong Langmuir turbulence from

setoiid hwnnosuc spectra in 1 ym laser produced plasma

j Dr. and, -V Gomes, J.C. Kieffer, L. Berge, C. Arnas

V. Quemenar, J.P. Dinguirard, M. Annengaud

[•niversife P. Sabatier,CPAT, UA 277 du CNRS

j if< route cie Narbonne, 31062 TouJouse-Cedex, France

and GRECO ILM, Eco!e Polytechnique, 91128 Palaiseau, France

and D. Pesme

CPT, Ecole polytechnic, 91128 Palaiseau, France

We present experimental resuiis on the time resolved second harmonic emission U obtained with the GRECO laser at 1 p and for irradiances between 10 and

16 z iC W/cm . The study has been performed with a high resolution spectrographic sy.steu). The temporal resolution on the 2«u emission is obtained with a streak camera. At high irradiances the spectra obtained at 90° of the laser axis with iron targets are composed of two narrow lines and a third broadened line whose red siiift increases strongly with time. The variation of the red shift (tX) of this last component of the spectrum with its broadening (AX) shows three different b regimes. For small red shifts one obtained (flX) v (AX) ; when the red shift increases, the slope change and one has (A)) >v (ft>.) . Finally at high red shifts )v(&}) . This is interpreted as beingS the signaturb e of the evolution of 5 b1 the strong Langmuir turbulence, and in particular of the presence of caviton collapse followed by Landau damping. The usefulness of the 2iv emission to gain insight into strong turbulence is discussed. - 125 - ECLIM18: P-2--10

I-IYDItODYttAiHK INSTABILITY OF CO1TTACT AREA OP TV7O DIP - PEPJiHT D31ISITY ACCELERATED PLOWS A. I:. Ale shin, Ju. G. Gamaliy, S.u.Zaitsev, ii. V.Lazareva, I.G.Lebo, V.B.Rozanov, S.K.Titov, ^.I.Chebotareva Krzhizhanovsky Power Institute, 117327 Lioscow. Lebedev Physical Institute, 117924 IJoscov/.

Target compression by means of laser radiation is associated with the development of hydrodynamik instability. The processes reduce hydrodynamik efficiency of a target and its amplification factor as well. Ex- perimental studies of the process at laser targets are thought to present considerable difficulties. The phenomenon is subject to theoretical registration (1). The present work has been conducted to study the formation of contact mixing area separating two different density flows affected hy a shock wave. The shock wave propagating through a low-pressure chamber of a shock tube transfers from one gas into the other, forming the contact mixing area. On refrac- ting from the end of the low-pressure chamber, the shock wave interacts with the contact mixing area. In order to perform diagnosis, use is made of Tepler method and interferometry. Working gases involve helium, argon, krypton, xenon. Initial gas distribution is performed with the help of a thin film or rapidly removed partition wall. The characteristics of the process of forming the contact mixing area formed on shock wave passing through the thin film or contact area formed during the partition wall removal have been determined. Mixing intensification caused by the interaction of the shock wave with the contact mixing area versus contacting flow density ratio has been determined. The effect of turbulent mixing on the reduction in the quantity of shock compressed gas behind the reflected wave versus contacting flow density ratio has been estimated.

I. lG.B.Ac&aHacBeB, H.T.EacoB, E.r.PaMajniS, O.H.KpoxHH, B.E.PosaHOB, "CHMMeTpHH H VCTOifaHBOCTL CJKaTHfl Jia- 3epHHX TepMOtfflepHHX MsnneHEH" (Siinmetry end stability of lasar thermonuclear target compression)* IlHCLMa B £3T$, T.23, Bun.II, 61^(1976;.

- 126 - ECLIM18: P-P-11

RECORDING OF SURFACE MOTION BY DOPPLER LASER INTERFEROMETRY M.M. Abazekhov, M.I. Belovolov, V.I. Vovchenko, T.B. Volyak, I.K. Krasyuk, A.V. Kuznetsov, P.P. Pashinin, A.M. Prokhorov, A.Yu. Semenov, V.E. Fortov Institute of General Physics of the USSR Academy of Sciences, Moscow, USSR

Doppler laser interferometer is reported have been used in recording of free surfaces movement of the targets subjected to high-power pulsed laser radiation. Optical communication lines with an object studied are realized on the basis of gradient fiber waveguides. The results of the velocity of impact wave front propagation over a sample are presented. These results are used to estimate the values of ablation pressure caused by laser irradiation of the target. The studied processes are modelled by means of computational hydrodynamic codes taking into account laser radiation interaction with the target material and real equations of the substances under study.

- 127 - ECLIM18: P-2-12

MEASUREMENT OF THIN FOIL MOVEMENT VELOCITIES INSIDE A CYLINDER CHANNEL V.I. Vovchenko, T.B. Volyak, I.K. Krasyuk, P.P. Pashinin, A.M. Prokhorov, A.Yu. Semenov Institute of 6eneral Physics of USSR Academy of Sciences, Moscow, USSR

An electrocontact method was used to measure the velocities of thin polymer foils having various thicknesses inside a cylindrical channel. The foils had been preliminary accelerated by an ablation action of pulsed laser radiation with an intensity as high as 4.10^1l/l//cm . The obtained results were compared with those of numerical modelling of the studied process. The channel inlet shape was shown to have an influence on the value of the measured velocity.

- 128 - ECLIM18: P-2-13

THIN FOIL DECELERATION DYNAMICS IN XENON ATMOSPHERE V.I. Vovchenko, I.K. Krasyuk, A.L. Nee, P.P. Pashinin, A.M. Prokhorov, A.Yu. Semenov, V.E. Fortov Institute of General Physics of USSR Academy of Sciences, Moscow, USSR

The results of electrocontact measurements of thin foil movement inside a cylindrical channel filled with deuterium are presented. The foils were accelerated by pulsed laser radiation of intensity (0,1-0.6) .lO^W/cm The obtained results are interpreted on the basis of one-dimensional computational code of the studied process involving a real equation of xenon state. The deceleration dynamics studies are shown to provide a basis for a quantitative determination of the moving foil mass. Approximate formulae are presented to estimate this value. The deceleration technique makes it possible to measure the value of an efficient exponent of gas adiabat with unknown thermodynamic characteristics.

- 129 - ECLIM18: P-2-14

SPONTANEOUS ELECTRIC POTENTIALS OCCURRING AT LASER ACCELERATION OF THIN FOILS IN A CYLINDRICAL CHANNEL V.I. Vovchenko, P. Heil, I.K. Krasyuk, P.P. Pashinin, A.M. Prokhorov, A.Yu. Semenov Institute of General Physics of the USSR Academy of Sciences, Moscow, USSR

High-precision electrocontact detectors have been developed to measure spontaneous electrical potentials caused by the processes of charge separation in a plasma corona of a moving target. Application of these detectors enabled to attain spatial distribution of charges in the corona and the effect of laser pulse shape on the target. Analysis of taking spontaneous electric and magnetic fields into account has been conducted within hydrodynamic approach of plasma substance motion in the configuration studied.

_ 130 - ECLIM18: P-?-

CURRENT GENERATION IN LASER PLASMA USING THE PREACTION OP LOW RADIATION PULSE ON THE TARGET

E.M.BarIdb.udarov9 G0V,Gelashvili, G#GoGumberidze, M.IeTaktakishvili Institute of Physics, Academy of Sciences of the Georgian SSR, Tbilisi, USSR

Laser-emissive conversion of light energy into the current energy is characterized by the low efficiency o Hence, the investigations aimed at the efficiency increase in the laser frequency band are important,, In this paper the possibility of the emission current amplifying using the preaction of low energy laser pulse on the target is considered., The pulsed CO^TEA laser was used in the regime where two pulses wxth the energies 4,5 and 27 J were obtained. The delay time between the pulses varied in the interval from 1 to 50 /Vseco Copper target was placed in the vacuum chamber with the residual gas pressure Pa1O'5Torr. In this radiation regime, two current pulses were observed with the delay time strictly corresponding to the interval between the laser pulses, the second pulse amplitude being much greater than that of the first one. In this case when the delay time was 6+8 /\sec, the current amplification more than three times was observed. This corresponds to the power and efficiency increase by an order of magnitude. Meanwhile, the target material vapour expands up to 1 cm, and the plasma fills the whole descharge gap (15 cm) with the velocity 106- 10*cm/s. Probably, the action of the first laser pulse favours both the increase of energy contribution to the plasma and the charge compensation during the cur- rents flow. The magnitude of Y=O,25% for the efficiency was obtained© The same experiments were conducted at the gas pressure PsiO'^Torr,, In this case the current amplification effect was weaker. The experiments were carried out under the conditions when plasma and vapour parameters (created by first pulse) were not controlled,, Hence, these con?- ditions could be far from optimum. It follows that there is a possibility of the further increase of the conversion efficiency using this method.

- 131 - ECLIM18: P-2-16

REGISTRATION OF SPONTANEOUS MAGNETIC FIELDS IN LASER PRODUCED PLASMA ON THE "DELFIN-1" INSTALLATION N.G.Basov, E.G.Gamaly, A.A.Rupasov, G.S.Sarkisov, A.S.Shikanov, V.T.Tikhonchuk P.N.Lebedev Phys.Inst., USSR Acad.Sci., 117924 Moscow S.Denus, T.Pisarchik, J.Wolowski S.Kaliski Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland

Spontaneous magnetic fields in laser plasma have been firstly registered with "Delfin-1" laser system, Nd-laser radiation with 6 composite beams (18 beams in each) and total energy ^1k«J, flux density—8,1 o" W/cra^ and pulse duration -^ 5ns was focused onto the target. As the targets we have used glass spherical shells with the diameter 2Ro=400-600 pm and wall thickness A Rp=1-3 /Jm« Spontaneous magnetic fields were measured by using the method of Faraday rotation of the probing beam polarization plane. For this purpose we have made a diagnostic system including a device for producing probing beam at 2 CO0 and 3 OOo frequencies, a polarometric, shadow and interferometric registration channels. Such a system makes possible to measure the probing beam rotation angle with the spatial resolution over the target, and the plasma density profile to reconstruct spontaneous magnetic fields. The obtained plasma faradaygrams in totally crossed polarizers indicate complex structure of the magnetic fields in spherical targets under multibeam irradiation. In the faradaygrams along with large-scale changes of the rotation angle over the plasma there is a small-scale structure -^100 jum in size, which indicates a significant change in the magnetic field over the distance^100 urn. Average magnetic field, according to the estimates, constitutes ~ 100 kG. A theory is proposed that allows us to estimate the effect on the polarization plane rotation angle of the plasma density gradient in the direction perpendicular to the probing direction.

- 132 - ECLIM18: P-2-17

INTERACTION OF THE SHORT PULSE CO,, LASER RADIATION WITH HIGH-Z TARGETS

O.Badziak, S.Denus, D.Dzwigalski, O.Farny, J.Kostecki, tv1.Mamczur, P.Parys, D.'.Volowski, R.Oarocki, Z.Sikorski, K.Oanulewicz

Institute of Plasma Physics and Laser Microfusion 00-908 '.Varsavv.p.o.box 49, POLAND

The aim of this exoeriment is to investigate the atorcic number dependences of the interaction of the CO,., laser radiation with plane targets. Preliminary results of measurements of the absorption, the electron temperature and the energy spectra of fast ions will be presented.

- 133 - ECLJM18: '--.' -1b

NEW SPHERICAL TARGETS FOR INVESTIGATION OF LASER PLASMA COMPRESS I ON

W.Muniak, R.Suckanska

Institute of Plasma Physics and Laser Microfusion /IPPLM/ 00 908 Warsaw 49 Poland.

In this paper it was described the method of achieving spherical targets with an ablative layer of the reduced density /0,ii g/cia /, and thickness 10 /aw; works on achieving hemispheres made from plastics and metals of the diameter 600-1200 juai and wall thicknesses 10-50 (uui; and ways of assembling cascade targets. The ablative layer was made from porous plastic PS /poliethylene/. Hemispheres were achieved by the method of core coating and replica in the following stages: - chemical polishing of the core - coating the core with plastic or metal - putting on the transient layer - occluding in resin - grinding the profile to the core diameter - resing out the hemisphere with the grind.

The hemispheres made from PSj PMM, Ag, 'Cu, \ut PS-Ag; PS-Cu; Cu-PS; Ag-PS; PS-AU-PS and other were achieved in thise method. It has obtained possibility to construct various models of cascade targets in wide range of diameter sizes and wall thickness with receiving hemispheres.

- 134 - ECLIM18: P-2-19

COLLIDING FOIL EXPERIMENTS WiTH 5TRONG B1DIMEN5IONAL EFFECT5

B . Fara!, R . Fabbro Ecole polytechnique & GRECO I. L. li. 9! 128 PalaiseauCedex - France

F . Cottet, J.P.Romain E.N.5.M.A. rue Guillaume 7 85034 Poitiers - France

In order to obtain high pressures , colliding foil experiments have been achieved , with a 0.26 jim laser accelerating a thin foil of CH on a structured foil of Mo . The main parameter used in these experiments is the initial spacing between the two foils . We find a strong dependance of the induced pressure with this spacing , due to the bidimensional stretching of the accelerated foil . This effect is evidenced by recording the luminosity of the induced shock at the rear of the impacted foil on a streak camera and proves that this shock decreases rapidly when the initial spacing increase . A bidimensional lagrangian code has been developped and agrees with our results .

135 - ASF.KS t'"

"i..' Ceil.-?-- '••'•• •:;•'• -IT! i^criiiuogv. London •..' -.ad

M. Grande, F>. J- Ror-o, P. T. Runsby i'lit-herford Apple;w '. ;,:-•>• •.->••• hi. L cor., i/idcor

Optical streak phc^ogr.Tfhy and ^-absorption ;-dge spectro?cr> "?.•:- been used to observe shock coalescence induced by ^fcapf-ri 1;-. -r pulses at the Rutherford Appleton Labci atory' s "e.tr-.1 'r,^,-, Facility. The nev:ly installed cluster beam arranpt-raL-ni ?llnwb six beams of green laser light to be foctissed O'v.o -• j'.ivic ?p.-"t. The bigh power beams .::-in be timed relative x.v e/'.b • ^hi-,: to produce a .iI.aped pulse. The pulse has a leading edf.e J.I;1 a r:ab -nLansity i-->.ak with 3 ratio of 1:10. The p.;ak generates ••-. =?. ; '..•••• • 'v.>ck with a high propagation velocity than the weaker shock pi.-r>dii.-.."i by the leading edge of the pulse. As a result the t\«c .-hocK-- coalesce = The shock coalescence is observed with optical .-Hnak photography by using multiply stepped planar targets to record shock break out from the rear side of the target. The tiem-ity of the target material is obtained by measuring liie shift in the K-absorption edge. Preliminary results wjli be presented.

- 136 - ECL1M18: P-2-21

2D STUDY OF THE LASER SHOCK WAVE BREAKOUT AT THE REAR FACE OF A METALLIC TARGET

F. Cottet, L. Marty, M. Hn.llouin, J.P. Romain, Laboratoire d'Energetique et Detonique, 86034 POITIERS, FRANCE.

J. Virmont, R. Fabbro, B. F&ral, Laboratoire P.M.I. ,Eccle P'..lytechnique, 91128 PALAISEAU, FRANCE.

Two-dimensional effects of the laser shock propagation in a solid target have been studied using time-space records of the luminosity associated with the shock emergence at the rear face of the target", obtained with an ultra-fast streak camera. From these experimental records, the shock wave velocity is determined from the measurement of the shock transit time through the foil of a given thickness. A complete spatial-time analysis of streak photos has been combined with computer 2D modeling1 of the hydrodynamics to investigate the lateral expansion of the shock breakout. The process of laser-matter interaction is not included in the code, so the initial conditions are taken as the applied pressure generated by laser driven ablation, generally modeled by a gaussian pulse reproducing the laser pulse shape with the same width at half maximum. The sensitivity of calculations free parameters (maximum induced pressure, pulse duration and focal spot diameter) has been tested.

Examples of the analysis are presented for 26.5 ym thick—aluminum, 26 ym-thick copper and 25.5 ym-thick gold targets irradiated by high powered 0.26 ym light from the GRECO ILM* laser, yielding an incident intensity of about 10 W/cm2 . The calculations, well agreeing with the experimental data, show the valadity of the numerical model and its initial conditions, and therefore the weak lateral expansion in these 0.26 urn laser-shock experiments. Ef- fects of nonhomogeneous energy deposition in the focal area have also been investigated.

•Groupement de Recherches Coordonnees Interaction Laser Matiere. Ecole Polytechnique, Palaiseau, France.

1. J. Virmont, B. Faral, Rapport GRECO ILM, 1985, 1.16.

- 137 - ECLIM18: P-2-22

X-RAY ABSORPTION SPECTROSCOPY OF LASER PRODUCED PLASMAS*

C L S Lewis, R E Corbett, E Robertson, S Saadat, D O'Neill

Department of Pure and Applied Physics, Queens University, Belfast and

J D Kilkenny and R W Lee

Lawrence Livennore National Laboratory, CA 94550, USA

A novel diagnostic technique employing a point X-ray emitting plasna source to probe, by projection, a second larger plasma under investigation before Bragg reflection off a flat crystal has been successfully demonstrated. A recorded spectrum shows a source and absorption spectrum allowing a measurement of the population density of absorbing ion species in the corona of the large plasma with a 1-D spatial resolution of < 10um. Point source brightness from M-shell emitters (eg Yb) irradiated by short duration, delayed laser pulses are adequate to freeze the motion of the expanding coronal plasma to < lOOpsec frame times in the absorption spectrum. Spectral resolution of » leV at photon energies of 2—3 keV are possible allowing observation of stark profiles near the target surface.

Comparison of the space-time history of ion species from Al and Si targets deduced from experiment and predicted by hydro codes with atomic physics will be presented. The interpretation of numerous satellite lines to the He-like ion resonance series observed In absorption and not normally seen in emission will be given-

Work partly carried out on the VULCAN laser at the Rutherford Appleton Laboratory, England and partly on the Janus laser at the Lawrence Livermore National Laboratory, USA (US Dept of Energy Contract No W-7405-ENG-48)

- 138 - ECLIM18: P-2-23

SPATIALLY SENSITIVE SPECTROSCOPIC X-RAY DIAGNOSTICS FOR LINE FOCUS EXPERIMENTS

M. Grande

Rutherford Applet.on Laboratory, Chilton, Didcot, Oxon 0X11 OQX, England

T. Tomie

Electrotechnical Laboratory. 1-1-4 Umezono, Sakura-Mura, Nihari-Gun, Ibaraki, Japan

E. Fill

Max Planck Institut fur Quantumoptics, D-8046 Garching-bei-Munchen, Wes t Germany

The use of line focus geometries in X-ray laser experiments, producing plasma columns of typical length 10 mm and diameter 0.5 mm, presents particular problems in high resolution imaging, especially when spectral information in the range 2-20 nm is also required.

Three approaches using non-focussing optics have been considered, penumbral imaging, transmission gratings and coded aperture masks. The penumbral imaging technique has been applied to an X-ray crystal spectrometer to give radial information on the plasma conditions, giving confirmation of a population inversion at radii greater than 100 jjm,

A transmission grating has been used to provide similar information on the homogeneity along the plasma column. It is hoped that a novel technique of grating fabrication can be applied to producing gratings with a very high line density; this would provide a dispersion sufficient to produce monochromatic images of the plasma, spatially separated at the image plane, and hence provide very good information on the spatial distribution of population densities radially and along the column.

Finally, a possible technique using pinholo apertures encoded with a uniformly redundant array mask is under consideration. This would, in principle, give a very high spatial resolution; moreover the resolution may be independent in the axial and radial directions.

- 139 - ECLIM18: P-2-24

DIAGNOSTICS OF GOLD LASER PLASMAS J.C. Gauthier, J.P. Geindre, P. Monier, C-. Chenais-Popovics, N. Tragin Institut d'Electronique Fondamentaie, Universite Paris-Sud 91405 Orsay, and GRECO, ILM, Ecole Polytechnique, 91128 Palaiseau, France.

In order to get diagnostic of gold plasmas by aluminium emission spectroscopy we used : gold microstrips (5, 10, 20 pm wide) embedded in aluminium targets, and aluminium alloyed with 3, 7, 15 and 50% of gold. This 1500 A thick mixture was overcoating a silicon substrate. X Ray spectrometers with flat crystals were used to record spectra in the range 4 to 7 A with radial or axial space resolution. A streak camera with a curved crystal spectrometer was used to get time evolution with high spectral resolution. The laser flux was between 3.10ll« and 2.1015 W/cm2 at 0.53 urn with 600 ps laser pulses. A large decreasing of aluminium emission in alloyed target was observed as compared to pure aluminium spectra. Temperature and density determined from aluminium spectra were found decrease with increasing gold percentage. At the maximum of gold emission the density was between 1021 and 5.1021 cm"3 and the temperature less than 350 eV. At this point the emission of nickel-like gold (2=51) was clearly observed in contradiction with all known models of gold ionization except the E.T.L. model which is assumed to be non- valid at the measured density.

The microdot spectra behave like the addition of pure aluminium spectra and pure gold spectra, so the lateral transport is probably not strong enouch to ensure temperature homogeneity in the focal spot. It results that diagnostics of gold by surrounding aluminium is ruled out. The gold spectrum from microstrip targets shows a decreasing ionization when we used successively 10 and 5 pjn wide microstrips. This decreasing ionization is also observed in alloyed targets of 50% gold i'n 50% aluminium to 3% gold in 97% aluminium. These results suggest that ionization may be enhanced by radiative contributions.

- 140 - ECLIM18: P-2-25 COMPARATIVE X-RAY SPECTROSCOPY OF VARIODS-Z ELEMENTS WITH ABSOLUTE WAVELENGTH CALIBRATION

J.E. Rainier, W. Lampart and R. Weber

Institute of Applied Physics, University of Berne, CH-3012 Berne, Switzerland

Plane targets of medium- to high-Z materials were irradiated with 1 J, 800 psec Nd:glass laser pulses at X = 527 nm to produce intense soft x-ray emission in the 5 - 15 A spectral range. This part of the spectra is of interest, for example, for x-ray laser schemes and x-ray lithography applications.

The x-ray spectra were recorded in one-shot exposures onto DEF film with a (time-integrating) miniature Bragg spectrometer. Medium-Z targets (Ti to Cu) show a pronounced line structure whereas spectra of higher-Z targets (Ag, Sn, Au, W, Pb) are nearly continuous. The spectral resolution is limited by the size of the emitting region. We show that the range of intense x-ray emission can be varied almost at will within this wavelength interval 1.

Absolute spectral calibration was performed by superimposing the well-known K-shel1 spectra of a low-Z material side by side to the other spectra. This wavelength calibration allows the investigation of laser-produced plasmas as pump sources in soft x-ray laser schemes involving resonant photopumping.

_ 141 - ECLIM18: P-2-26

.LASER SHELL TARGET IMAGES IN. X-RAY SPECTRAL LINE SELF-RADIATION K. Goetz+, G. Korn++, M.P. Kalashnikov, AOM. Maksimchuk, Yu.A. Mikhailov, A.V. Rode, G.VO Sklizkov, ASG, Tikhonov, S.I. Fedotov, E. Forster4"

P.NO Lebedev Physical Institute, USSR Academy of Sciences, Moscow +Friedrich-Schiller Universitat, Jena, DDR ++Zentralinstitut fur Optik und Spectroscopie Daw Zu, Berlin, DDR

In laser fusion experiments there is a problem of determination of high-dense plasma transparency for self-radiation. The calculation method of absorption and radiation of shell target laser plasma X-ray spectral lines is described in the paper, one takes into account resonance, bremsstrahlung and photoionization mechanisms of absorption. The calculation are carried out for glass shells with Na, K and Ca impurities for diagnostic purposes. There are given plasma images in radiation of Na, Si and Ca spectral lines which have been obtained in the "Delfin-1" laser facility experiments. It is shown that Doppler image shift in the lines, which the plasma is optically dense for, gives an information concerning corona implosion velocity, and, hence, - target mass ablation rate. The usage of optically thin spectral lines of Ca-K diagnostic impurities allows to localize the inner surface of a comperssing shell, heated by DD-gas, in images and to determine target compression efficiency correctly. Analyzing the plasma transparency for radiation of various ions included in a target as an impurity one can judge of target composition with respect to the possibility of active diagnostics as well as that of passive diagnostics by plasma images in self linear radiation.

- 142 _ ECLIM18: P-2-27

EXPERIMENTAL INVESTIGATION OF LASER THERMONUCLEAR TARGET PREHEATING

N.G0 Basov, SeYu. Gus'kov, M.P. Kalashnikov, Yu.A. Mikhailov, V.B. Rozanov, A.V. Rode, A.V. Sartory, GOV. Sklizkov, S.I. Fedotov P.N. Lebedev Physical Institute, USSR Academy of Sciences, Moscow

In laser fusion experiments the level of preheating of the thermonuclear fuel and the shell compressing it is the main showing of target compression efficiency. The results of investigation of electron, radiation and shock preheating in experiments on compression and heating of high-aspect ratio shell targets at the "Delfin-1" laser facility are given in the paper. The method of measurement of target preheating by fast electrons based on the analysis of superheat plasma radiation is considered. The estimates of radiation and shock preheating of compressing shells and DD-gas are given. The results show high adiabatic efficiency of thermonuclear fuel compression in the "Delfin-1" laser facility experiments.

- 143 - ECLIM18: P-2-28

SUPPRESSION 0? RECOMBINATION IN EXPANDING LASER-PRODUCED PLASMA

S.V.Bobashev, D.M.Simanovsky, L.A.Shmaenok

A.F.Ioffe Physical-Technical Institute, Academy of Sciences of the USSR, I9402I, USSR.

The recombination of ions and electrons in a far zone of expansion of the laser-produced plasma (IiPP) formed "by two crossing IiPP bulks was studied* Such plasma bulks were created by focusing two beams of a Nd:glass laser (5J»50ns, 10"W-cm"2) on a plane solid target into two spots located at a distance d=I...20mm. It was found using a spectroscopic technique (I) that at distances from the target R=I...I0cm the intencity of three-body recombination (the main recombination process in the far zone of expansion (1,2)) in the crossing bulks is I5.»»20 times lower than the doubled recombination intencity in a single bulk. At the same time an increase (2...3 times) of the average ion charge was detected by an ion collector. The suppression of the recombination and the gain of the average ion charge were found to be maximum at the certain distance between the focal spots (d=I2mm), The effect discovered can be explained, to our mind, by an increase of the electron temperature resulting from a friction between the crossing LPP bulks. Owing to the strong dependence between T and three- body recombination intencity (I ^l1 "*••$) such an increase leads to the suppression of the recombination process.

1. V.V.Afrosimov, S.V.Bobashev, A.V.Golubev, D.M.Sima- novsky, L.A.Shmaenok, Sov.Phys. JETP,91,p.485,1986. 2. S.V.latyshev, I.V.Rudskoi,Sov.J.Phys.of Plasma,II p.II75,I985. — 3. A.V.Gurevich,L.P.Pitaevsky,Sov.Phys.J3TP,46,p.1281, 1964.

- 144 - ECLIM18: P-2-29 INVESTIGATION OF THE RADIATION PROPAGATION IN THE CHANNEL OF THE HIGH POWER LASER.

A.Dubik, A.Sarzynski Kaliski institute of Plasma Physics and Laser Micro fusion, oo-908 Wersaw, P.O.box 49. POLAND

The paper presents the process of the high power laser channel optimization by means of the numerical method on the basis of propagation equations. Accuracy of the numerical method used hare-differential method - was analysed. In the optimizational investigations of the laser channel spatial filtering, relaying, apodization and other phenomena occuring in high power laser systems were taken into account. The channel was optimized in order to achieve high fill factor, cut-off level of the order of 10 , small loses of power on the system apertures and the high degres of homogeneity of the amplified radiation. Ihothe result of the above analysis there was achieved some information about the optimal parameters of the channel of the Nd glass laser, built in the IPPLM. The method presented above enables modelling of the laser channels and thus it is possible to determine optimal configuration of such a channel.

- 145 - ECLIM18: P-2-50 INVESTIGATIONS OF EFFICEENCY OF Nd GLASS LASER AMPLIFIERS.

A.Oubik, O.Godzik, O.Makowski, o.Owsik

Kaliski Institute of Plasma Physics and Laser Micro fusion, 00-908 Warsaw, P.O.box 49, POLAND

G.V.Sklizkov, N.Awtonomow, M.Mazur P.N.Lebedev Physical Institute. Moskwa, USSR

The paper presents the results of investigations of the influence of thermal effects, radial distribution of amplification in the beam cross-section, type of material of diffussive laser reflector and conversion coating containing quantum converters, on the parameters of multilamps laser amplifiers of various diameters of active media.

- 146 - ECLIM18: P-2-31 ACTIVE PULSE SHEAPING IN SUBNANOSECOND RANGE FUR H1(JH POWER Nd GLASS LASER SYSTEM

S.Denus. A.Dubik, D.Marczak, D.Owsik, 0.Piotrowski Kaliski Institute of Plasma Physics and Laser Micro fusion, 00-908 Warsaw, P.O.box 49. POLAND G.V.Sklizkov, O.V.Senatskij, B.J.Iwanow. N.E.Bykowskij P.N.Lebedev Physical Institute, Moskwa, US8R

Nd glass generator of subnanosecond pulses and YAG:Nd lasers with electro- and acustooptic ^-switch of

the resonator have been worked and they are tQ be applied for high power laser systems "Delfin" in the Lebiediev Institute of Physics /Moscow/ and for 4xK laser in the Kaliski Institute of Plasma Physics and Laser Microfusion /Warsaw/. In the system with the electro optic Q-switch, controlling the resonator losses in done periodically by means of electrical pulses of rise time t** 10 v/s given in the time interval 2L/c, where L is the resonator length and c is the light velocity. The following values of features have been achieved: time duration of the generator pulses 'v 5 x 30~ s energy up to 10 3, accuracy between synchronization of pulse train and the moment of electro-optic cell incorporation

- 147 - ECLIM18: P-2-32 LIQUID CRYSTAL ISOLATORS FOR HIGH POWER LASER SYSTEMS.

T.Cesarz, A.Dubik, O.Kusnierzx, O.Owsik, A.Szymariski*

Kaliski Institute of Plasma Physics and Laser Microfusion, 00-908 Warsaw, P.O.box 49, POLAND

The paper presents the results of investigations of liquid crystal isolator. Cholesterol liquid crystal ability selective reflection of light, depending on its state of polarization, was used. Liquid crystal isolator for Nd:glass laser system was obtained. The temperature dependence optical density of chosen liquid crystal layer was investigated. Maximum suppresion of radiation opposity circularly polarized then is twisted structure of crystal about 80 time was obtained.

Technical University of Rzeszow

- 148 - ECLIM13; 0-3-1

SPACE AND TIME RESOLVED MEASUREMENTS OF ABLATION UNIFORMITY

A J COLE, M H KEY

RUTHERFORD APPLETON LABORATORY, CHILTON, DIDCOT, OXON, ENGLAND

D BROWN, P NORREYS, E WOODING

ROYAL HOLLOWAY BEDFORD NEW COLLEGE, EGHAM, SURREY, ENGLAND

A monochromatic. X-ray pinhole camera, coupled to an X-ray streak camera, has been used to make measurements of the spatial uniformity of the mass ablation rate on spherical and planar targets.

The spherical targets were Irradiated at = 5, 10^ wCm^ with 0.52um laser light using the 12 beam Vulcan laser. Analysis of the results obtained allows a quantitative measurement to be made of the. uniformity of laser absorption over the surface of the target, as a function of focussing conditions and irradiance.

Planar target experiments have been performed at 0.249um using the Sprite KrF laser at an irradiance of = l.lO^ Wcm"^. Major nonunlformities are apparent in the spatial distribution of ablation rate corresponding to gross structure in the laser beam.

- 149 - ECLIM18: 0-3-2 OBSERVATION OF ION CORRELATION IN SHOCK COMPRESSED LASER

PRODUCED PLASMA

T.A. Hall, A. Djaoui, R.W. Eason, C.L. Jackson, B. Shiwai

Department of Physics, University of Essex, Colchester, U.K. S.L. Rose, A. Cole and P. Apte

Rutherford Appleton Laboratory, Chilton, Oxon, U.K.

The VULCAN laser at the Rutherford Appleton Laboratory has been used for shock compression and heating of thin foil aluminium targets coated in N-parylene. The frequency doubled beams from the neodymiuzn glass laser are incident on each side of the sandwich target; shock waves are generated in each layer of plastic and travel inwards, to collide in the thin 2um layer of aluminium. This aluminium layer compressed to several times solid density and heated to temperatures of a few eV. Under these circumstances the ion coupling parameter T>>1 (T = Q^e^/RokT: where Q is the ion charge and Ro is the ion sphere radius) and the ion motion is strongly correlated, resulting in short range order with a preferred ion pair spacing.

We have used a pulsed extended X-ray absorption fine structure (EXAFS) to experimentally observe this short range order. A backlighting source, producing a pulsed quasi-continuum X-ray source used in these experiments is obtained using an extra beam(s) from the VULCAN laser, incident on a uranium target located several millimeters away from the sandwich target. The X-rays from the backlighting target pass through the shock compressed region of the sandwich target and the spectra are observed using a mini crystal spectrometer.

Ion correlation effects have been observed during compression and densities ~5 x solid density have been measured.

_ 150 - ECLIM18: 0-3-3

LASER ACCELERATION OF THIN.FOILS IN CONIC TARGETS V.I. v'ovchenkc, T.B. Volyak, Yu.S. Kas'yanov, I.K. Krasyuk, P.P. Pashinin, A.M. Prokhorov, A.Yu. Sernenov Institute of General Physics of USSR Academy of Sciences, Moscow, USSR L. Pina Fac. Nucl. Sci., Tech. Univ. of Prague

The results of V-T diagrams direct measurement of thin polimer foil motion inside a conic channel are presented. The foils were accelerated by neodymium laser radiation with an intensity of & 1011W/cm2 and pulse duration of 22ns. It has been established that when interacting with laser radiation the foil transforms into a vapour cloud with the density by two orders of magnitude less than the initial one. The maximum velocities of nonevapourated matter regions movement are recorded to be as high as (1-1,5),107cm/s. The obtained data have made it possible to assume a mechanism of compression and heating of gaseous deuterium filling the target up to thermonuclear tempe ratures. The conducted investigation has continued the work started in /I/.

1. S.I. Anisimov, V.I. Vovchenko, A.S. Goncharov etal. "Investigation of neutrons at laser action on conic targets", 1978, Pis'ma v OTPh, v.4, ser.7, p.388-392

- 151 - L-CLIM18: 0-3.-4

Magnetic Field Behavior Beyond the Laser Spot

S.R, Goldman* and R.F. Schmalz

Max-Planck-Institut fur Quantenoptik D 8046 Garching, Federal Republic of Germany

Abstract

We have found a self-consistent, analytic solution for the two dimensional, cylindrically symmetric, time varying problem of the interaction of a laser plasma with its self-generated magnetic field, at lateral locations away from the laser spot. The plasma is described by a two-fluid model, with the magnitude of the electron velocity much greater than the ion velocity. We find increased spatial gradients in the density and velocity around the magnetic field maximum. This leads to a double humped ion-velocity spectrum, which could be interpreted in terms of a two-temperature electron distribution, in qualitative agreement with experiment.

* On leave from Los Alamos National Laboratory, Los Alamos, N.M. 87545, USA

- 152 - ECLIM18: 0-3-5

Measurements of self generated magnetic fields in 0.25 pi laser

produced plasmas using the Zeeman effect

J. Briand, J.C. Kieffer, A. Gomes, C. Arnas, J.P. Dinguirard

Y. Quemener, L. Berge, M. Armengaud

Universite P. Sabatier, CPAT, UA 277 du CNRS

118 route de Narbonne, 31062 Toulouse-Cedex, France

and GRECO HM, Ecole Polytechnique, 91128 Palaiseau, France

Experimental results on magnetic fields are obtained from measurements of the ft Zeeman effect in a 0,25 urn laser produced plasma at a laser irradiance of 2 10

W/cm . We study the transition Is2s S = Is2p P of C ions. The detection is done with a Rowland spectrographic set up associated to a UV light amplifier allowing to record the whole spectrum between 2200 A and 2300 A in one laser irradiation. Polarization analysis is done with a Wollaston prism. We show that the Doppler effect produced by the plasma expansion enables us to resolve spatially the field distribution. The data reveal the presence of axial and toroidal fields.

The axial field has an amplitude which decreases along the laser axis (0,5 MG at maximum). This field is probably produced by a dynamo effect. The toroidal field amplitude varies very weakly with the distance from the target plane, presen- ting however a maximum (0,35 MG) in the corona. Furthermore the toroidal field envelope appears to withdraw from the plasma axis as one goes away from the target.

- 153 - ECLIM18: 0-3-6

X-ray emission and radiation transport in laser-produced plasma

K. Eidmann, R. Schmalz and G.D. Tsakiris

Max-Planck-Institut fur Quantenoptik D-8046 Garching, Fed. Rep. of Germany

Plane targets made of Al, Cu or Au have been irradiated by 300 ps laser pulses at intensities of up to 1015 W/cm2 and at two different wavelengths (1.3 urn and 0.44 um). The emitted x-radiation has been measured with spatial and temporal resolution using a transmission grating spectrometer in the photon energy range 100 eV < htf < 4000 eV. The experimental spectra and the efficiencies of conversion of absorbed laser energy in- to x-radiation will be presented. A characteristic gold burn-through depth has been obtained using layered targets consisting of a thin gold film (0.1 to 1 |im) on a Cu-substrate.

The results agree with numerical simulations performed with the 1-D hydrodynamic code MULTI, which treats the radiation transport by multi-group diffusion and which uses stationary non-LTE absorption and emission coefficients .

This work was supported in part by the Commission of the European Communities in the framework of the Asso- ciation Euratom/IPP.

- 154 - THURSDAY

MAY 7 ECLIM18: R-4-1

KrF LASER/PLASMA INTERACTION STUDIES AT THE UNIVERSITY OF ALBERTA

A.A. Offenberger, R. Fedosejevs, P.D. Gupta*, R. Popil, J. Santiago, Y.Y. Tsui

Department of Electrical Engineering University of Alberta Edmonton, Alberta Canada, T6G 2G7

The University of Alberta research program is based on an optically compressed single-beam KrF laser system which will be upgraded over two years to a 24-beam system incorporating a lkJ amplifier. Recent plasma experiments have been concerned with parametric instabilities and x-ray energy conversion and transport. Stimulated Brillouin scattering has been studied in some detail - in particular, the dependence of spectra and reflectivity on laser intensity (SlO^W/cm ), target material, focal position, and angle of incidence (0) - and comparisons are made for conditions with and without pre-formed long scalelength plasmas. The x-ray energy conversion efficiency has been determined using an array of filtered detectors for targets ranging in atomic number from 4 to 82 with focused laser intensities of 10 -10 W/cm . Azimuthal dependence and temporal characteristics of the x-ray emission were also measured using x-ray diodes and an x-ray streak camera. The effect of radiation transport on plasma hydrodynamics in high-Z plasma has been studied by measuring burnthrough of gold coated plastic targets as a function of laser intensity (10 -10 W/cm ). Experimental results will be presented and discussed.

•permanent address Bhabha Atomic Research Centre, Bombay India

- 157 - ECLIM18: R-4-2

KrF LASER-PLASMA X-RAY SOURCES - GENERATION AND APPLICATIONS

F O'Neill

Laser Division, SERC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon 0X11 OQX, UK

In this paper I will review recent developments at the Rutherford Appleton Laboratory, Central Laser Facility, on the use of krypton fluoride (KrF) lasers for generating laser-plasma X-ray sources. These sources have been used for various applications such as X-ray microscopy, X-ray lithography and spectroscopic studies of relevance to XUV laser research.

It has been clearly demonstrated at a number of laboratories using frequency converted Nd lasers, that short wavelength laser light is converted more efficiently to X-rays in a laser-produced plasma than long wavelengths. This result suggests that the KrF laser operating at a wavelength of 0.25jjm would be particularly efficient In generating laser-plasma XUV sources. As well as the advantage of short output wavelength, KrF lasers also operate at a high efficiency of > 1% and highly focussable beams are produced because of the good optical quality of the gaseous laser medium.

At this laboratory we have used the 200J e-beam-pumped KrF laser Sprite to generate single shot high intensity laser-plasma sources for X-ray microscopy applications. High conversion efficiency (> 5%) from KrF laser light to X-rays in the wavelength range 2.3 - 4.4 nm (the so-called "water window" region which Is optimum for X-ray microscopy) has been measured for a number of target materials and X-ray images of hydrated biological specimens have been successfully recorded in X-ray resist showing sub-micron resolution. We are also using low energy (~ U/pulse) high repetition rate (20Hz) discharge-excited KrF lasers as a means of generating quasi-CW laser-plasma X-ray sources. The output of a commercially available laser (eg Models EMG 150 and EMG 210 from Lambda Physik) Is focussed onto rotating targets and the X-ray source thus produced has been used for test printing of fine line images into X-ray-sensitive resist. These repetitive sources appear to be highly suitable for future scientific (eg X-ray microscopy, spectroscopy, X-ray calibration) and industrial (eg X-ray lithography) applications.

The details of these X-ray sources generated by KrF lasers will be described and the results of some recent applications will be presented. Prospects for future applications will be discussed in relation to anticipated KrF laser developments In such areas as higher energy (~ 1-lOkJ pulses), higher average power (1-10 kW) and higher intensities (100J, lpsec pulses).

- 158 - ECLIM18: R-4-3

KRYPTON FLUORIDE LASER DRIVERS FOR ACHIEVING VERY HIGH ENERGY DENSITIES

R . J . Jensen

LANL

- 159 - ICLIMIO: ;-4-4

LASER-MATTER INTERACT ION STUDIES USING A MULTI-KILOJOULE KrF LASER AT LOS ALAMOS NATIONAL LABORATORY

L.S. Blair, D.C. Cartwright, S.V. Coggeshall, L. Foreman, P.D. Golds tone, J.A. Hanlon, A. Hauer, R. Kristal, J. McLeod, * W.C. Mead, L.M. Montierth , L.A. Rosocha, A. Young

University of California, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States of America.

Recent studies, at Los Alamos and elsewhere, show that 0.25 urn is near optimum for coupling of laser energy into target compression. Because KrF lases at 0.25 jim, and has the potential for 10 per cent wall-plug efficiency and relatively low capital cost, Los Alamos is investigating the feasibility of the KrF laser as an ICF driver. To this end, Los Alamos is constructing a proto- type short-pulse high-power KrF laser (called Aurora) which will serve as an end-to-end technology demonstration of the applica- bility of large-scale KrF laser system for ICF applications. AURORA is designed to employ optical angular multiplexing and serial amplification by electron-beam-driven KrF laser amplifiers to deliver 5-ns duration multi-kilojoule laser pulses to ICF targets.

Los Alamos is planning a series of laser-target interaction experiments, at the 5 kJ level to begin in early FY 1988, using the AURORA KrF laser. These efforts are intended to help provide an assessment of the ultimate utility of KrF laser technology for ICF. The planned experiments fall into the following four categories: (1) Target coupling and hot-electron-preheat conditions, for KrF-irradiated targets. (2) Behavior of laser-plasma instabilities and coupling that can be affected by special capabilities of the KrF laser driver. Special properties of the KrF laser system that could beneficially affect the laser-target coupling include: (a) beam quality; (b) wavelength spread of the laser light (bandwidth); (c) the ability to incorporate the Induced Spatial Incoherence (ISI) concept. (3) Study, in planar geometry, the physics of hydrodynamic instabilities that ara potentially damaging to target performance and must be understood to be controlled. (4) Optimize the x-ray conversion and other aspects of indirect-drive target performance, to minimize the laser energy required for capsule ignition and high gain.

Laser system assembly and integration is currently under way. Initial coupling experiments are expected to commence in early FY 1988 and experiments on hydrodynamic instability growth should begin in early FY 1989 as more complex instrumentation becomes available.

^Permanent address: University of Arizona

- 160 - ECLIM18: P-3-1

CONDENSED- AND COMPRESSED-GAS LASERS

N.G.Basov, V.A.Danilychev P.N.Lebedev Physical Institute, USSR Academy of Sciences, Leninsky pr. 53, 117924 Moscow, USSR

The research into condensed- and compressed-gas lasers, which led to the development of excimer lasers, the electron-beam-controlled carbon-monoxide and dioxide lasers, and the high-pressure lasers operating on electronic transitions of inert gases, are reviewed. Physical principles underlying the methods of popu - lation inversion in dense gases and the pumping mechanisms are considered. The parameters of high- -pressure pulsed, pulse-train and CW gas lasers are cited.

1. N.G.Basov, V.A.Danilychev, E.P.Glotov, A.M.Soroka. Trudy FIA1J SSSR, _U2 , 95 (1983). 2. N.G.Basov, V.A.Danilychev. High-Power Lasers in Technology. In: Science and Humanity, Znanie, 1985.

- 161 - ADVANTAGES OF A MULTIPASS AMPLIFIER

IcV. Epatko, P,;P,. Pashinin. R.V. Serov Institute of General Physics of the USSR Academy of Sciences, Moscow, USSR

Multipass amplifiers are of great interest as they allow compact efficient high power lasers to be made. In this paper the method of calculation of multipass amplifier parameters based on some peculiar properties of Frantz-Nodvic equation is suggested. The optimum efficiency operating mode of the multipass amplifier is found. The dependence of the backward travelling wave gain and pulse shape distortion on the amplifier parameters is presented. The performances of multi- and single- pass amplifiers are compared.

- 162 - ECLIM18: P

IODINE LASER DRIVER RERUN V. Hermoch, M. Chvojka, B. Kralikova, 0. Krasa, L. Laska, K „ Masek, 0. Musil., S. Polak, !< o Rohlena 3. Skala, J. Schmiedberger Institute of Physics, Czech. Ac. Scien., Na Slovance 2, Prague 8

A new type of iodine photodissociation laser system was developed with the goal of using it as a driver. The laser chain is composed of an oscillator and four amplifiers,, The oscillator is controlled by a Kerr cell, but it operates in a self-mode-locked regime producing a short train of pulses ~2 ns, 20 mO. After a pulse selection and shaping in a spark gap triggered Pockels cell at the first amplifier a single pulse is produced 1,5 ns in length and 100 mO of energy. This passes through a second Pockels cell for optical insulation the pulse is then progressively amplified in the three following amplifiers to obtain a pulse < 1 ns, 50 3 on leaving the chain. The terminal amplifier of the laser chain is pumped by sealed off Xe flashlamps (5 kV, 300-us) . The reduction of the voltage and the possibility of using the compact flashlamps for pumping in a UV region (5,3% efficiency) are the advantage which is paid for by the length of the pumping pulse., The pulse is long enough to allow for acoustic disturbances to evolve inside the laser vessel during the pumping time. The gaseous laser medium consists of the i-C3F7l laser gas, SF5 for added thermal capacity and He for line broadening. The optical coupling in the last amplifier is enhanced by carefully designed reflectors., The ad- verse influence of the acoustic waves inside the last amplifier on the beam divergence and focussability of the beam can be reduced by selection of the laser mixture to minimize the disturbances. A multispot measurement indicated the beam divergence of 5.10~^ rad. The pulse contrast is still to be determined.

- 163 - INVESTIGATIONS O:-1 PULSED LASER NEAR-SURFACE PLASMA FORMATIONS

L.Ya. Min'kof A.J\ Churaakov Institute of Physics. BSSR Academy of Sciences, Minsk, 220602, USSR

The analysis is &J.ven of experimental studies of the dynamics of pulsed near-surface plasma formations due to irradiation o.C absorbing targets in the air?by laser radiation (LR) fluxes of 0.1 to 1000 MW/crn intensity [1-5]» The conditions are considered of the experimental studios of the character and dynamics of initial plasma generations formation of the absorbing plasma layer and structure of laser near-surface plasma formations„ Experimental dependences are discussed of the initial evaporation and plasma formation time on the LR power density and laser pulse shape, the target material and conditions of the gas-dynamic flow. The character of these dependences is associated with the erosion nature of initial plasma formation in a wide range of LR wavelengths from 1.06 to 10,6 yum. We also report a direct experimental confirmation of the erosion nature of initial plasma formation by the methods of nanosecond kinetic spectroscopy. The connection is analyzed of the experimetally observable turbulence of the near-surface laser-generated plasma flov; and the fluctuating nature of initial plasma formation under threshold conditions with the instability and the locally inhomogeneous character of initial evaporation and plasma formation. The results are reported of investigating the dependence of pressure on metal surfaces upon the LR power density of quasistationary pulses. It is shown that the experimental LR power density dependence of pressure differs from that calculated using the thermal model, and the growth of the screening effect of plasma formations is accompanied by stepwise initiation of pressure oscillations on the target surface with a frequency up to 10 kHz, 1. L.Ya.Min'ko, A,.L\i.Chumakov, Yu.A.Chivel', Kvant. Elektronc, v,11, Ho,11, p,2241 (1984) 2. L.Ya.MirrivOj, YueA.Chivel', A.N.Chumakov, Zh.Prikl. Spektrosk,, v,42, No-1, p.55 (1985) 3. L.Ya»MinvLoj B»T.Fedyushin, Yu.A.Chivel1, A.N.Chu- makov, KvarrUSlektron., v,12, No.3, p.639 (1985) 4« M.A.Yelyushevich, L,Ya.Minfko, G.S.Romanov et al« Izv.Akad* Nauk 3SSR, ser*fiz., v.49,No.6, p.1132 (1985) 5. L.Ya.Min'ko, •,WoChumakov, Ya.A.Chivel' et al. Abstracts of the All-Union Seminar on Physics of Fast Plasma Processes, Grodno, p.47»55 (1986)

- 164 - ECLIM18: P-3-5

THE EFFECT OF TARGET'S INITIAL STATE ON THE PROCESS OF LASER INDUCED PLASMA FORMATION M.R. Bedilov, H.B. Beysenbaeva, M.C. Sabitov, P.K. Khabibullaev, S.A. Karamisheva, R. Abdupataev Institute for Nuclear Physics, Tashkent

Using the relationship between laser induced plasma lifetime and the rate of ionization and recombination processes, taking place in the target, we have studied the effect of the target's initial state on the processes of laser induced plasma formation. The initial state of the target, which is undergone to the light irradiation of the 109-10i:L Wt cm~2 density were varied by means of /-irradiation using Co source up to the dosed l"ob to 5.10y P. Combined analysis of the results obtained for different initial states of the target has shown that -radiation induced defects make easy the process of fasma of higher degree of ionization. However the increase of plasma cloud density in this process enhances the recombination rate in triple collisions. The interpretation of the results are carried out on the basis of solid state radiation defects physics and on that of balance of laser radiation energy, which is spent for producing and heating of plasma.

- 165 - ECLIH18: P-5-6

SECONDARY OPTICAL BREAK-DOWN ON LASER PLASMA BOUNDARIES IN ThE AIR AND PLASMA MIRROR FORMATION UNDER MICROSECOND LASER PULSE A.M. Prokhorov, V.A. Spiridonov, V.B. Fedorov, I.V. Fomenkov Institute of General Physics of USSR Academy of Sciences, Moscow, USSR

On microsecond Nd-laser pulse interaction with laser spark plasma, after optical break-down of the air, there occurs the secondary break-down of the cold gas on the cold gas/plasma interface, first behind the spark and then in front of it. The primary and secondary break-downs were produced by two laser pulses with a controlled time delay between them. Besides, the radiation focusing areas for the first and second pulses were about 1 cm apart along the lens axis. The second pulse was focused in the vicinity of the front boundary of the discharge plasma. Nevertheless, the secondary breakdown occurred first on the back plasma boundary, and then, in the time needed for the second pulse to attain amplitude maximum, on its front boundary. Comparison of the conditions of secondary breakdown on the boundaries of laser spark in the air enables to conclude that the secondary break-down occurs on the back boundary due to radiation self-focusing in a quasistationary plasma. The secondary breakdown is shown in the experiments to occur at the second pulse time delay of (3+40) .us, the threshold intensity being within (0.1+3) 107W/cfo . It is experimentally established that unlike the primary breakdown, the secondary one on the back boundary of laser spark may lead to the effect of plasma mirror on a gas target, if there is strong enough feedback between the reflecting dense plasma of the secondary break-down and laser. In this case a sharp increasing of oscillation power is observed with transition to Q-switching regime and mode locking, and as a result, increasing of the rates of ionization front propagation up to the values of 2.107 cm/s along the laser beam.

- 166 - ECLIM18: P-3-7

LOW-THRESHOLD MANDELSTAM-BRILLOUIN STIMULATED SCATTERING ON NEODYMIUM LASER PLASMA MIRROR AND SPECTRAL CHARACTERISTICS OF ULTRASHORT PULSE GENERATION A.M. Prokhorov, V.B. Fedorov, I.V. Fomenkov Institute of General Physics of the USSR Academy of Sciences, Moscow, USSR

The experimental data on spectral characteristics of ultrashort pulse generation are for the first time obatined on neodymium laser with plasma mirror, starting from the instant of initiation of mode locking regime on a plasma mirror by means of auxiliary nanosecond laser. It is revealed that at nanosecond radiation pulse interaction with plasma preliminary produced on a carbon target (I ~ 10 W/cm ) a subnanosecond reflected signal occurs with a spectral shift of *& 2A toward larger wavelengths in respect to the incident radiation spectrum. A reflected pulse is injected into the active medium of the master laser. Since Stokes shift is small compared to neodymium glass amplification band width, this pulse is effeciently amplified in the active medium as a result of double passing along the resonator, and repeatedly interacts with the target plasma. This process is then multiply repeated with the radiation amplitude growth, shortening of the pulse duration, spectrum broadening and further spectral shift to the "red" part of the spectrum within the amplification band of neodymium glass. During several cycles of this type, generation of ultrashort pulses reaches a stable regime in which radiation pulse power exceeds 104 times that of the initiating radiation, the duration shortens to 20 ps, and the spectrum width ^ 100# approaches that of the neodymium glass amplification band. The experimental results indicate that the mechanism of ultrashort pulse reflection from the plasma mirror at the stage of its generation establishment starting from the initiation instant is Mandelstam-Brillouin scattering (MBS) in the plasma with the temperature not lower 20 eV and electron density not less 4.1019cm . MBS reflection of nonlinear plasma mirror occurs in the first ultrashort pulses at relatively low light flux densities. A low- threshold character of MBS on plasma mirror might be associated with thermal self-focusing of the initiating radiation on a target in plasma.

- 167 - ECLIM18: P~3~S

ULTRASHORT PULbc INITIATION IN NEODYMIUM LASER WITH PLASMA MIRROR US TNG AN AUXILIARY NANOSECOND LASER A.M. Prokhorov, V.B. Fedorov, I.V. Fomenkov Institute of General Physics of USSR Academy of Sciences, Moscow, USSR

A carbon target was irradiated with a free-oscillation neodymium laser with plasma mirror to produce an effect of low-threshold reflection of laser radiation from target plasma in one of a series of microsecond spikes. An occurring in this case short reflection spike is established to give rise to generation of a series of high-power ultrashort pulses, when being injected back to the laser aperture. This effect was used to attain controlled initiation of ultrashort pulses by a nanosecond pulse (t£*15 ns, I ?s lO-^-M/V/cm ) from an auxiliary single-frequency neodymium laser. The amplitude of the injected pulse is enough to develop generation during several passes of radiation over the laser cavity. The pulse life-time during the development of generation decreased from 0,1+0.4 ns to 20 ps, and their power increased by 3+4 orders of magnitude, reaching 1010+ lO^W. Fitting the amplification coefficient of the laser active medium, one can control the rate of the generation power growth. Thus, ultrashort pulses from a neodymium laser with plasma mirror have been for the first time externally launched at a given and exactly fixed instant. This gives new advantages of application of these lasers in physical experiment.

- 168 - ECLIM18: P-3-9

GSGG:Cr3+, Nd3+-LASER WITH SBS-MIRROR ANU PLASMA SHUTTER

S.Yu. Natarov, P.PO Pashinin, E.I. Shklovsky Institute of General Physics of USSR Academy of Sciences, Moscow, USSR

Optical breakdown in the media is known to cut off the tail of the laser pulse initiating the spark. This property of the optical breakdown together with SBS-mirror reflecting backward the incident laser radiation can be applied to generate light pulses of variable duration within a nanosecond(subnanosecond region. Our GSGG:Cr, Nd-laser consists of a master oscillator (f6 3x50mm) and a pair of amplifiers (tf 5x60mm and j6 6x60mm) decoupled by means of polarizers and Fresnel rhombs. The combined effect of phase conjugation in an SBS-active liquid and breakdown in the air resulted in a high-contrast Stokes pulse of the width, as recorded at the laser output, determined by the distance between the optical breakdown position and that of SBS-mirror. The breakdown of the air was produced in the focus of a telescope placed on the light pulse way to a cell containing SBS-active liquid. The main performances of the laser are: - laser pulse width, variable 0.4+15 ns (FWHM) - pulse energy ( A =1.0613,um) 65+240 md - pulse repetition rate 0.2-4 p.p.s. - total pump energy per one shot 45 D - pulse to pulse energy/width stability 80% - beam quality - diffraction limited.

- 169 - KLZ,n "\m HIGH-SPEED SYSTEM FOR IITEP^SOMETRIC PLASMA PHOTOGRAPHY II "••••--' PUS ION EXPERIMENTS

AOT.'., :••••• .lav, B.L.Vasin, R,G«May, A.I.Smelkov, G»V»^;, ,..L3kov, S,I,Fedotov

: P,KaLe?^ac, Physical Institute, USSR Academy of Sciences.? Moscow

;The optical system for 7-frame high-speed (up to i.»iO' frame/s) and high-resolution (up to 100 line/mm) registration of interferometric laser plasma images, •;--.ed in laser f sion experiments at the "Delfin-1" laser facility is dencribed in the paper. The constractive methods used at device construction are analyzed* The characteristic series of photography of laser interaction with a shell target is given, and one made an attempt to explain the experimental results.

- 170 - ECLIM18: P-3-11

THE SYSTEM OP SCHLIEREN-PHOTOGRAPHY FOR SHOCK-WAVE REGISTRATION AT THE "DELFIH-I" MSER FACILITY A.D.Valuev, B.L.Vasin, V.M.Zubkov, M.Yu.Mazur, Yu.A.Mikhailov, G.V.Sklizkov, S.I.Fedotov, S.A,Chaushansky P.N.Lebedev Physical Institue, USSR Academy of Sciences, Moscow, USSR

One of the most interesting physical phenomena accom- paning laser heating of the dense plasma, particularly, under certain conditions, in laser fusion experiments is formation of strong shock waves (S¥) in gases. At gas densities of about 101'-"!©1" cm""3 the velocities of such SW reaches the values of about 10 '-10° cmjfs, the temperature behind the front - 102 ev. One should note that the interest to SW formed by the laser as to the physical phenomenon has the applied meaning connected with the possibility of laser plasma parameter determination, in particular, ion temperatuCT, absorbed energy and so on. The existing methods of laser plasma parameter determination by SW do not always give an accurate result. It is connected with that fact that the physical idea of such SW formation is not completely clear. This, in turn, stimulates interest to physics of SW generated by the laser plasma* All this predetermined the program of SW investigations at the "Delfin-1" laser facility. The problems connected with development and usage of multiframe photography system (SMP) are considered in the given paper. In particular, The major demands to the whole system and to its separate elements are substantiated; the 19-frame SHF is described (it is used at the "Delfin-1n laser facility); the preliminary results of SW investigations, obtained in experiments on compression of high-aspect ratio shell targets are reported.

- 171 - ::-EVKi-.-: •••Ki:r.: •' APPLICATIONS OF THE REFRACTIVE FRINGE DIAGNOSTIC

P.F. Cunninp;!-. :. M.M. Michaelis, R.N. Campbell, J . Wai tham , ?•!. •; i tc att

Physics Deparl.ir. r.t, University of Natal, Durban, Natal, South Africa

The refractive fringe diagnostic is used to study the electron oenr-.ity profiles of laser-produced plasma''' v~' . ;he technique is experimentally simpler than interfer vnetry but nevertheless may yield (r>) timp-resolvea ant. a' We report here an improved analysis to accommodate non-well-behaved probe beams and the novel application of the technique to the study of laser-driven and other shocks^ .

(i) M.M. Mi chap]is, 0. Willi, Opt. Comm. 36 153-8 (1981) (.-?) P.F. Cunningham, R.N. Campbell, M.M. Michaelis, J. Phys. E 1_9 957-960 (1986) (3) R. Benattar, C. Popovics, J. Appl. Phys. 5£ 609-14 (1983) (4) R.N. Campbell, M.M. Michaelis, P.F. Cunningham, Submitted to Phys. Fluids (1987)

- 172 - ECLIM18: P-3-13

HOLIGRAPHIC DIAGNOSTICS OF PLASMA DENSITY DISTRIBUTION USING ABEL INVERSION

•A Chen Zezun , A. Giulietti, L. Nccera, D. Giulietti** and M. Lucchesi**

Istituto d i Fisica Atomica e Molecolare, C . N . R . , Via del Giardino 7, 56100 Pisa, Italy *Permanent address: Shanghai institute of Optics and Fine Mechanics,P.O. Box8211, Shanghai,China * * A L s o at Dipartimento di Fisica, Universita di Pisa.

A computer method of Abel transformation to obtain the plasma density distribution from holo graphic phase-interferograph pattern is presented. The calculating formula, error estimation and pattern processing are discussed. "his method is simple and accurate enough in compari- sion with other methods of tables and matrix. In the low density plasma experiments, many important results have been observed by using this method. The formation and evolution of a very low density channel along the beam axis and more complex structures in differet initial density are studied.

- 173 - ECLIM18: P-3-14

DECONVOLUTION OF ELECTRON DENSITY -PROFILES WITH SHARP GRADIENTS FROM LASER PLASMA INTERFEROGRAMS S.F. Goncharov, R.V. Serov, V.P. Yanovsky Institute of General Physics of the USSR Academy of Sciences, Moscow, USSR

Electron density distribution gives a valuable information on plasma hydrodynamics during laser plasma interaction. It can be easily deconvoluted from the interferometric picture if the profile is smooth and interferogram is simple enough. However, in the recent experiments at UMI-35 laser facility interferometry shows the peculiarities resembling the shocks spreading out laterally from the focal spot. In these sites the interferometric fringes are merged making ordinary deconvolution impossible. In this paper the method of deconvolution of the described peculiarities is presented. It is based on a simple assumption that fringes are merged but are not intersected. At the electron density distribution achieved the sharp gradients corresponding to deconvoluted peculiarities can be seen. To check the procedure a ray tracing through deconvoluted electron density distribution was used. Comparing the interferogram achieved with the initial one and artificially changing the values of electron density gradients the validity limits of procedure can be estimated.

- 174 - ECLIM18: P-3-15

ON THE POSSIBILITY TO OBSERVE SPONTANEOUS MAGNETIC FIELDS IN COMPRESSED LASER TARGET S.S.Kotelnikov*, .I.G.Lebo, V.B.Rozanov * Polytechnical Institute, Leningrad P.N.Lebedev Phys.Inst*,USSR Acad.Sci.,117924 Moscow In compressed laser target the generation of 10- 100 MGs spontaneous magnetic fields is possible. Conventional optical methods can not be applied to studying spontaneous magnetic fields in compressed plasmas. We have considered two problems: i) the effect of magnetic fields on the direction of oC - particles emission from the targets; ii) the scattering of the electron beam of E ^> 100 keV in the magnetic fields of the laser target. The problems are assumed to possess axial symmetry. •> v 1. Magnetic field has one component H= (OjC'} \\\g ) and Hy=ZIHtt('r-)SmK'flr» For a single harmonic n we have calculated angle distribution of the flux of charged particles CdLfMQVldlo/cLS)* fK($ f) .where dlo/l£ is isotropic distribution for Hn, =0,o^(r£-n)//^([njj]» is the magnetic field localization region; RT, zhe Larmor radius at the amplitude magnetic fiela value). At tl$•*0.1 O5\9; reaches ~ 30%, It is shown that the number or maxima of ff»(M(5,3) one can find the number of the harmonic which is the most intensively developed under the target compression. The H rt, value may be estimated by the maxima amplitude!/1/. 2. When spherical target ol* the laser-plasma jjet is irradiated by the electron beam of the energy B > 100 keV along the axis of the system, the differential crosssection of the scattering oLS'/dx is determined, as seen from estimates, by the value and geometry of spontaneous magnetic fields occuring in plasma. Maxi- mal deviation angle of the scattered electrons t^wtyj r\ is determined by the harmonic number and parameter & at £ < 1 (for even "n" the 5^*x is less than for odd "n" ( W&'<1 )).As seen from analytical and numerical simulations the scattering differential cross- section is of extremal character, the number of maxima in d6T/i{£?is unambiguously connected with the number of the magnetic field harmonic /2/ The proposed methods of corpuscular diagnostics of spontaneous magnetic fields will make possible the study of magnetic fields in the inner compressed regions of the laser targets.

LKotelnikov S.S. ,Lebo I.G., Rozanov V.B. Kratkie soobshcheniya po fizike, 1983, N 1, p.3» 2. Kotelnikov S.S., Lebo I.G., Rozanov V.B. Kratkie soobshcheniya po fizike, 1986, N 12, p.58.

- 175 - ECLIM18: P-3-16

THE CALIBRATION OF SILICON PIN DETECTORS FOR X-RAY PLASMA DIAGNOSTICS 1 2 L. Pina , E. Krousky, 0. Renner , I. Benc, J. Urbanec Fac. Nucl. Sci., Tech. Univ. of Prague, 115 19 Prague Inst. of Physics, Czechosl. Acad. Sci., 180 40 Prague Tesla Vacuum Technique, 180 72 Prague, Czechoslovakia

The use of Si PIN diodes as detectors of X-rays in laser plasma diagnostics is discused. The current spectral sensitivity /l/ is defined in accordance with two-thickness model /2/. The thickness of the first layer reduce the efficiency of the detector at lower energies, the second one at higher energies. Following successful development of Si PIN detectors tailored for laser plasma research there has been continous effort to obtain their absolute calibration. Several different methods have been used. The dead layer thickness was determined by measurement of treshold range of electrons and eC-particles in Al and Si layers in detector. Calculation of relevant X-ray transmission has been used to obtain spectral sensitivity curve for low energies. At higher energies direct calibration using characteristic lines CrK* , CuK«. and MoKK from standard X-ray tubes has been made. The radiation has been collimated and monochromatized by Ge(lll) crystal. The intensity of X-rays at the PIN diode surface has been calibrated by Nal(Tl) scintillation detector with known spectral response. The contribution due to fluorescence radiation and harmonics were determined by means of multichannel analyzer and subtracted. To attain high accuracy of the measurement, the connection chain has been established including the radioactivity standard- rfFe emanating 5.9 keV photons at fluence rate 13283 s in 47T steradians, the counter efficiency, X-ray source strength and diode sensitivity. No attempt has been made to eliminate the noise of the detector by use of chopping technique as done in /4/ believing that used experimental arrangement is closer to real plasma diagnostic conditions. Experimental results are in good agreement with theoretical curve.

1. Pina L., Cs. cas. Fyz. A35 (1985), 363. 2 D.M. Corallo, D.M. Creek, G.M. Murray, J. Phys. E: Sci. Instr. 13(1980), 623. 3. I. Benc et al., in preparation 4. T. Jach, P.L. Cowan, Nucl. Instr. Meth. 208(1983).

- 176 - ECLIM18: P-3-17

X-RAY IMAGE-CONVERTER CAMERA "ALMAZ-R" BASED ON AN IMAGE CONVERTER TUBE WITH DEMOUNTABLE PHOTOCATHODES

V.K. Chevokin, BSE. Daahevsky, V.A. Podvyaznikov, A.M, Prokhorov, A»V. Prokhindeev General Physics Institute of the USSR Academy of Sci- ences, 117942 Moscow, Vavilov str,38, USSR

An image-converter tube (ICT) with demountable photocaRhodes has been developed for diagnostics of X-ray and UV radiation of laser plasma. An electron- optical system produces a focusing field of the quasi- apherical capacitor, Au or Csl with the thickness of o o 3OOA and 1100A, respectively, are used as photocatho- desv The photocathodes are deposited on a lOOOA-thick nitrocellulose substrate. The static spatial resolution is not worse than 10 pair lines/mm. For temporal image analysis, two pairs of mutually perpendicular plates are inserted into the ICT and separated by an aperture diaphragm set in the crossover plane* The size of the diaphragm is 0»3 mm. An image-converter camera nAlmaa-RH has been developed on the basis of this ICT, Dynamic tests of the camera have been performed in the experiments on recording soft X-ray radiation of laser plasma produced at focusing a high-power ultrashort laser pulse ( A t = 50 ps, E = 50 mU, \ « = 1*06 jaxa) on a plane target. Temporal resolution of the camera is about 50 ps, dynamic range is not worse than 50.

- 177 - ECLIM18: P-3-18 MODULATION TRANSFER AND RESOLUTION IN X-RAY PTNHOLE PHOTOGRAPHY OF LASER-PRODUCED PLASMAS

J. Mika and J.E. Balmer

Institute of Applied Physics, University of Berne, CH-3012 Berne, Switzerland

The uniformity of laser irradiation of solid targets is of considerable importance for laser fusion experiments. Non- uniformities in laser energy deposition result in non-uniform heating of the plasma. This in turn may lead to spatial structure in the x-ray emission which can be observed, for example, by x-ray pinhole photography.

With the aid of specially designed "resolution" targets (50 ym, 20 ym, and 10 ym Al microdot arrays on a 2 ym mylar foil), we have experimentally determined the contrast transfer characteristics of an x-ray pinhole camera equipped with pinhoies from 50 down to 4 ym in diameter. We find that 10 ym structures are easily resolved (modulation transfer of more than 20%) with pinhoies smaller than about 10 ym.

With the pinhole camera thus characterized we have recorded the x-ray emission from 527 nm/200 ps laser-irradiated targets of various Z. At an irradiation of 101* W/cm2 we observed strong modulation in the x-ray intensity and a substantial (3x) increase in the size of the emitting zone with increasing Z. This is in marked contrast to similar shots at 1054 nm.

- 178 - ECLIM18: P-3-19

DESIGN ASPECTS OF A 2-D X-RAY SPECTROMETER

C L S Lewis, B R Fraenkel+, P F Cunningham0

Department of Pure and Applied Physics, Queens University, Belfast

Permanent Address + Racah Institute, Jerusalem o University of Natal, Durban

Multiple diffraction images of a laser produced p3asma have previously been observed using two Umwcg reflections in a single Germanium crystal I'll. General application of the technique at specific wavelengths is limited by availability of suitable crystals with the appropriate symmetry requirements- We present here a generalisation of the technique whereby we employ two separate crystals whose planes of incidence are rotated with respect to each other, giving high angular resolution in orthogonal directions over a wide wavelength range. An emitting X-ray source, eg an imploding spherical shell giving rise to coronal and core emission may be imaged in each of its emission wavelengths with < 10um spatial resolution and in principle a gated detector could record the emission in a = lOOps time frame.

Preliminary images of simple targets will be presented and the limitations of the technique (eg resolution, sensitivity) discussed. It is shown that the instrument can be compact and easy to align.

I'll B S Fraenkel: Appl Phys Lett 41(3), 234, 1982

- 179 - ECLIM18: P-3-20

GALVANOPLASTIC REPLICA MIRRORS FOR LASER-PLASMA SOFT X-RAY IMAGING

H.Fiedorowicz, S.Nagraba

Institute of Plasma Physics and Laser Microfusion 00-908 Warsaw, p.o.box 49 p.o.box 49, POLAND

R.Hudec, B.Valnicek

Astronomical Institute of the Czechoslovak Academy of Sciences 25165 Ondrejov, CZECHOSLOVAKIA

We report the results of our work on X-ray reflection microscopy and their applications in laser plasma diagnostics. The new galvanoolastic replica technology develooed at the Astronomical Institute of the Czechoslovak Academy of Sciences which allows to produce X-ray mirrors at relatively very low costs is presented. Using this technology the grazing incidence axisymmetric X-ray mirrors for X-ray astro- nomy and X-ray microscopy applications with diameters between 20-240 mm were produced. Up to now several small parabolic test mirrors and the hyperboloid- ellipsoid type X-ray microscooic mirrors were fabricated. In order to estimate the performance of the metallic replica mirrors the X-ray imaging experiments have been carried out. The tests were carried out at the IPPLM with the experimental arrangement for laser-driven implosion investigations.

- 180 - L:>:LIH18: P-3-21

PARTICLE DIAGKOSIICS OF LASER PBOOTSED fLASIA B.Yu.Sharkov Inst.of Sheer, and Exper.Phys. (XTE?), Moscow, 117259,USSR

In connection with the problem of intend ve heavy ion beam formation froa Bcn-stationar laser produced plasma flow an experimental divice, including a aoiaber of diagnostic systems capable of assuring the charge state, transverse phase volume, ion energy spectra of expanding laser produced plasma, ae well as of the heavy ion beam, formed from that plasma, has been developed, In Thomson spectrograph, cylindrical e»ergy~asass-analyser, electron converter apparatare and in ae^tral atoms analyser microchannel detectors are used,, because of the microchannel plates (MOP) advantages in comparison with other mmlti;jliing detectors based on the secondary electron emission effect. In present work spesial attention is payed to the ab« solute determination of the ifiCF efficieacy in heavy ion registration regime. The conditions for nemtral particles registration by meams of the MC?~detector are suggested by the experimental results on the contribution of kinetic and potential emission mechanisms in the MCP gain at different charges an energies of the incident ions. 1. L.Z.Barabash, Yu.A.Bykovakii, D.G.Koshkarev, B.Ynt,Sharkov et al. "Laser produced plasma as an ion source for heavy ion inertial fusion** Laser and Par- ticle Beams (1984), v.2, p.1,49-59. 2. L.Z.Barabash, A.A.Golubev, Yu.A.Zacharenkov, B.Yu.Sharkov, A.S.Shikanov "MicroChannel analyser for particles and x - ray emission of laser produced plasma" lapid Cc^rxstnications of Lebedev Phys. Ihst., 1985, N 5, 16-20.

- 181 - ECLIM18: P-3-22

APPLICATION OF THE CR-39 TRACKS DETECTOR TO REGISTRA- TION OF LC'.V ENERGY CHARGE PARTICLES

O.Farny, E.'.Voryna

Institute of Plasma Physics and Laser Microfusion 00-908 Warsaw, p.o.box 49. POLAND

Yu.A.Zakharenkov, A.A.Erokhin

P.N.Lebedev Physical Institute MOSGOW, USSR

The registration efficiency of the CR-39 tracks detector for low energy /E< 20 keV/ charge particles has been investigated. It appears that this type of detectors may be used for registration of ions in the low energy region till 1 keV, and it seems to be very usefull in the laser-plasma experiments. Preliminary results of measurements low energy protons from the high frequency source and the laser produced plasma will be presented.

- 182 - _tCLliii8j_ P-3-23 LASER FUSION PIji.8M.ik OIAGJSOSIIUS JTHOJia"" THE SECONDARY FUSION REACTION PRODUCTS

N.G. Basov, S.Yu.Gus*kovi B.V* II*in, A.A« Levkovsky, V.B. Rozanovs, V.E. Sherman, O.B. Vygovsky. Lebedev Physical Institute, 111924* Moscow, USSR; Zavod-VTUZ, 195108, Leningrad, USSR. It is known fi3 that the ratio of the yields of secondary particles H> to primary ones N^ $ gives the direct opportunity to define the value pR by small values of this parameter,, It is expedient to investigate the diagnostic dependancies ^/Ej-FCp) for model uniform targets with constant mass over" a wide range of plasma temperatures and densities taking in- to account such factors as slowing-down of primary particles and changes at that of secondary reaction cross-section,electron gas degeneration, boundary effects etc. Calculations in this paper are based on the numerical solution of the kinetic equation for fusion particles in limited plasma with the help of Monte- Carlo methodf2]. As the calculations showed, the parameter N^/Nj preserves good criticality from the point of view of diagnostics not only when R/A« 1 ( A- range of primary particles), but also when R/>, -1 due to strong dependence of secondary reaction cross-section upon energy. This criticality is sometimes preserved also when R/AV1 due to the beginning of electron gas degeneration. All this favourably differs the method of density diagnostics due to secondary partic3es yields from methods where only the effect of slowing-down of primary charged particles in plasma is used [1] •

1. S.7u» Gus'kov, VoB. Rozanov, Proc. of Lebedev Phye. Inst0> v»15-'i-,p#1i5 (1982) 2. N.G. Basov et al., SOT. J. of Plasma Physics, v.6, p. 90 (1980),

- 183 - 7OSS";..:. r <••(}&<:.'-'TiC'S OF PLASMA OP H ASPEC•••-•... • .-. r7-.-!fiK?S 1¥. THE LASER P *y c:.^.-.;;-.; -•:' ':!. c;? c? NUCLEAR PAHTICLE^ v 0BB,VyRovek;7v 8, •-.i<. Cu;,-. kov. N,V« Zmitrenko , 1).,V* i.'l'in., Vr, Y -. '-rp.v, :, it Levkovsky ? T,VSMJ • -icaen-- ; hos V .•BvRo'/.&rj.ov » * Lj w,it; a:ion

; Lebedev Fhyaicfi^ Insiitute. 11? 924,MoskovfU3o. i; ».vod-VTLZ"( 'iS^-'f-S, Leningrad,USSR

The %",otit:'- 'sjrlo method is employed to caion- jiits spectrn. b:i^ yioij^ ui products cf prima:r;Y and cocondary therr:. •••::'}. <• !\v yd actions for a number of high-aepeet-ra;: - ta:-.--c t« r^ied in the Dolphin unit, it is shown thn- vn he ;--:i3e of deuterium target filling, the avenge valui? of the product of the density by the «ize of DJ) plasma at the moment of the maximal energy release can be determined from the ratio of the yield of yecondery neutrons born in •H (d, n)^He rea^tioh to the primary ones.. The ; laid of secondary protons frotn * Ho (dv p)^'Ho reac- r.'on depends on a degree of deceleration of 3JIe " •.-xis in the ac^.ve zone and it can he. otripi n/wd for • xagnostics of *'ie piaama temperature,, '-or £>'.!' target filling • is shown that the spectra and yields of nuclei' cf recoil from the elastic .impact •"itli r.eutfoijp; e.vi sensitive to the aJ.,ate of the ; -..ell and can be utilized for its diagnostics.

- 184 - F.CLIM18: P-3-25

ON A NEW METHOD OF ANALYSIS CHARGED PARTICLES BEAMS DINAMICS M.Yu. Romanovsky Institute of General Physics of the USSR Academy of Sciences, Moscow, USSR

It is important to be capable of controlling beam parameters while creating gase discharge and inverse population by a beam of charged particles that's why the detailed knowledge of its dinamics is necessary. The investigation of plasma light-induced beams is another aspect of this problem. Traditional analysis is connected with selfcongruent potential of beam particles and is difficult. The method sudgested is linked with quasyclassical nonrelativistic description of a charged particles beam taking into account only coulomb interaction by analogy with selfaction of light beam in the nonlinear optics problems. Shrediger equation is introduced for beam wave-function which consists of individual particle wave-function and Pouisson equation for selfcongruent potential with right part - the second degree of the introduced wave-function. It is possible to construct an equation for normalized beam width for the problem of particles beam spreading in semispace. One can obtain a beam width and amplitude dependence of coordinate to study its stability in respect to initial perturbation „ For the problem of spreading of long cloud charge in pipe with cross keeping it is possible to determire the low of longitudional despersal of cloud with known initial form in dependence the distance from the entrance. These resultes allow to simplify (as compared with traditional methodes) the problem of beam parameters optimisation for different purposes - creating inverse population in laser plasma of definite geometry, analysis of electro-optics transformers and so on.

- 185 - YKdEl: ' ARGET ACCELERATION IN HEAVY ION FUSION Yu.VeAfanasiev V* A* Isakcv, K.A#Khachiyan P.N»Lebedev Ph' ancal Institute, Academy of Sciences of the USSR, Ldninsky pr. 53, 117924 Moscow, USSR

The report describes analytical model of plasma formation under the action of the ion beam onto the three-layered target ( an inner fuel layer - - a low-density absorber in the middle to where the moat part of the beam energy is deposited - - an outside i.--.javy tamper which plays the role of a "hard wall" limiting the motion outside). The results obtained allovf us to calculate the hydrodynamic efficiency es a function of the beam and target characteristics, ands thus, to choose the target structure optimal from this point of view. It is shown that 3uch targets are effective if the stopping pov/ers of the materials used as tamper and absorber differ essentially. Since they prac - fcically differ by 2-3 times, the hydrodynamic efficiency increase would not be higher than 15-25 % as compared to the simplest double-layered target usage. If the initial ion energy is fixed then those targets would be optimal, where the structure corresponds to the ion pulses of relatively high energy. Analytical results obtained give good explatation of the numerical experiment data /1/. The role of thermal conductivity and the radiative transport is estimated. 1. W.Metzler, J.Meyer-ter-Vehn. Laser and ^article Beams, 1984, £, part 1, p«27. 2» Yu,,V. Af anas lev, V.Aalnakov, KBA.Khachian» Plasma Physics (Fizika Plazmy), 1987, 13, p.101; Preprint PiAW, 198b3 N 40.

- 186 - ECLIM18: P-3-27

HYDRODYNAi'lIC EFFECTS IN CONIC THERMONUCLEAR TARGETS A.V. Bushman, I.K. Krasyuk, B.P. Kryukov, P.O. Pashinin, A.M. Prokhorov, V.F. Minin, A.Yu« Semenov, V.E. Fortov Institute of General Physics of USSR Academy of Sciences, Moscow, USSR

Computational simulation of hydrodynamic equations with widerange equations of states taken into account are used to investigate peculiarities of the substance flow in conic thermonuclear targets. The obtained results make it possible to account for the process of plasma generation with thermonuclear parameters inside conic targets at explosive and laser casting of their coating. Solution of this problem using equations of ideal gas state for the substance constituting a target is shown to lead to unadequate description of the process,

- 187 - .:'..."': -fll: O^1 I'/U-.GK'i": FOR POWERS SHORTWAVE iAs :::

WeGf Basov*, • ''.:•... ",\\6 • K.OV* S G*V* Danilov ! + ! N.N. Demchenk'--'-, .:.Vt - nn t.i-enko . V,Ya* K-.; ••••. T.Y* Mishcherilo • , Y*B* i'ioaaiiov*, A. A* Same ::;.f; Li

^Keidysh Institute of. Appiied Mathematics,. USSR Ac. of ooi«, Moscow, USbH

•Lebedev Phys' ^a.1 /•>.^;"ut-J biiSR Ac, of ^-.:iS Moscow, USSR

The coni,>i.',er ;.iaf,i£ii.i-. v ;.v-'ii) sii.'Ui.ia^ion plays ax.; important par* ij: a>i iavo:-;tiRation oi1 complex problems connected with the laser tMV, .r_. An anaJysis of different concepts of a lese: •o.ie.^cnuclo;-.:' .rea'.-.toi ,y based currently on lorjuita of ao.ne comra;-. ;• •.v.xpc^-;j:ii«nts for a prediction ox the tar^s-c gain VE^-JC oi on with laaer energy. The gain value3 K. -• 100-300 o.v-e obtained niimerically for the simple nn.- .>••'_• "11 - ^ygiitG (CHp- —ablator and DT«-iee) and la^cr ::adi.^.,:.•-n ivavelengths of O.27~1.06 v. ••> with laaar enure • i....- Trora 2 to 20 MJ t 13• For this type of targets the <>;a...,u .reaches the value K = 30 for the laser wavelength I0.-6 MP, at ELAS= 20 MJ Cifjn* A physical and jna.thematicai uu.'dr:.! j.rclijrles a hyd— rodynamic description of a two-i-c^peratur-e piesma, an energy transfer by a classic tht;r-ii,or;c-!i.ductive mechanisn and takes into account a transpo.;.'-i o.r the fast super— -thermal particles (i.e. the thoi-ino-.iuclear reaction products and elect''ons generat-.-d at the resonance absorption of a laser radiation) i 3'J- Jiumerical methods are based on the completely conservative difference 3chernes of Lagrange's hydrody—

1. W.G. ^JOV, S,Yu» Gr'j'kov, G.v. Danilova et al», Quant ujr. )i\..r:.Xv*,, 19^:5, v.1^, K 6, p. 1289-1292. 2. S.Yu. lit J'.'.UV, Plasma r'hys - - i'995, v.11, N 6, p.745-/- - 3« Procee-i .;/ of i,eoedev ^!iy;..« Inyi*{ iloscow, Nauka, 1982 (v .i -..;), 1986 (v.170). r ; 4. A.A... Jaiucii . -i'.iis i'u.; ( Popov "difference methods for solution "•:' ^;'i• i >-• a.r,i • ij.roblems", Moscow, Nauica, 1980*

- 188 - ECLIM18: P-3-29

ON PARAMET2RS OP FOCUSING OPTICS OP A LASER PUSIO1J REACTOR H.G.Basov, N.I.Selousov, G.A.Vergunova.P.A.Grishunin, A.E.Danilov, I.G.Lebo, V.B.Rozanov, G.V.Sklizkov, V.I.Subbotin, S.I.Pedotov, V.V.Xharitonov P.N.Lebedev Physical Institute, Moscow, USSR;Moscow Engeneering Physics Institute, USSR

Energy "balance of a commercial laser fusion reactor is considered- It is shown that the energy of reaction products which is absorbed by the focusing optics of the reactor exceeds drastically the absorbed energy of the laser pulse. That is why the con- sept for final focusing optics changes significantly in the environment of the reactor from that in the environment of the research device. The reactor optics must retain high laser damage threshold and geometrical stability in conditions of high power driver pulses. A spectrum of the target X-ray radiation is calculated and on this basis X-ray damage thresholds were obtained for a raw of optical materials. Vari- ants of optics protection with the atmosphere of inertial gas under pressure 20-50 Pa are analyzed. It is proved that the effectivity of gas protection is significant if X-ray radiation has a thermal spectrum with temperature less than 5 keV. The comparative analysis of vacancy foundation rates and gas production rates under fusion neutrons is made for a variety of traditional optical materials. On this basis the minimal distances from the center of the chamber to the optical system are obtained. The laser radiation brightness which is needed for ignition of the reaction is employed to derive a relation between the minimal focal distance and desired laser damage threshold of the optical material. It is shown that fusion neutrons striking the focusing system cause substantial thermal stresses and deformations and this is the reason for limiting the final optics single element apper- ture.

- 189 - ECLIMlg. P :A-L'...

THERMAL CALCULATIONS FOR LASER MIRRORS

V.V= Knaritonov Moscow Engeneering Physics Institute, USSR

Various complicated systems of intensive cooling are used for thermal stabilization of high-power laser mirrors and heat rejection of absorbed power. Special attention in this work is paid to the regu- larities of hydrodinamics and heat transfer in typical systems of mirror cooling* Also its aim is to find the limits of cooling intensification and the influence of cooling intensification on temperature distributions in the mirrors and to calculate thermal deformations and strains in the construcional materials of the mirrors« Heat transfer and hydraulic ressistance were studied experimentally in the powder, chink, vr-nter, "brush " and "cross" cell structures made of copper, aluminium, silicon, steel and in structures made of invar with channels typically measuring 0.25-1 mm. All of these structures were cooled by water cor air. The maximuma of heat transfer values (2-3)iOpWt/(m2X) were achieved by water cooling (without boiling) of copper structures. The effective thermal conductivity of water in brush and wire-net structures was measured and the influence of collant mixing on the temperature distribution was investigeted. A theoretical discription of convective heat exchange for turbulent flow in porous media is presented. It makes possible to determine the limits of intensification for flat-parallel and jet flows in porous layers ond optimal parameters of mirror cooling system. There v/as found a range where jet flow is more preferable than longitudinal. A universial relation which linlcs heat transfer and hydraulic re- sistance in the systems of complicated channels is derived also. The influence of radial heat flow in reflecting Iryer, porous matrix and massive foundation on perraitable thermal loading in the case of local mirror heating v/as investigated. It is shown that a thickness of reflecting layer must be increased for safe mirror processing during local iigh thermal loading. The engineering methods of thermal deformation calculation for multilayer mirrors are developed- They provide simple analytical expressions for estimations of optical surface deformations due to thermal expansion and bending for stationary and pulsed loadings. The criteria of safe colled mirror processing are formulated.

- 190 - ECLIM18: P-3-31

THE CRYOGENIC TARGETS HEAT STABILITY UNDER LASER EXPERIMENTS E.R. Koresheva, A.I. Nikitenko P.N. Lebedev Physical Institute, USSR Academy of Sciences, Moscow

The problem of cryogenic target destruction into ICF chamber is investigated. The cryogenic target lifetime in chamber had been estimated. The possibilities of the target destruction because of the crystal growth in DT - layer and the gas mass increase into the target centre under the heating are need to take into account under the estimating of target lifetime. The double - layers targets lifetime with the value of mass 3 - 70 microgrammes is equal 0,037 - 0,7 seconds. Comparatively long value of target lifetime allows ones to hope for possibility of technical realization cryotarget delivery into laser focus without destruction.

- 191 - ECLIM18: P-3-32

CHARACTERISTICS OF LITHIUM FILLI PROM JTIOIJ ICF REACTOR FIRST WALL.

Berendeev SoA. ,Kagan D.N.,Shpilrain ^.ii. Institute for High Temperatures USSR Academy of Sciences Lebo IoG., Rozanov V.B., Sklizkov GoV. PoH.Lebedev Physical Institute USSR Academy of Sciences-

The experimental investigation of impulse energy influence on a liquid lithium film is going in IVTAN and FIAHoBrief descrition of the experimental installation for research of the behaviour of such film is described below. ICF reactor first wall response to microexplosion are evaluated, and compared with the simulation of microexplosion products interaction with lithium protection film by laser and laser plasmao The limitation on the working temperature of the metall film protection wich arise due to not good wetting of the wall by the Li-film and optical Li-vapor break-down by the driver irradiation are considered in the paper. We suppose that the temperature window in which the ICF reactor with lithium protection my be used is 400 to 6OO...7OO°C. The low temperature limit can be made lower. We should underline one possibly interesting usege of lithium film, flowing on the parabolic surface, as z. good mirror for CQj- and lid:glass lasers. Such mirrors can have reflective coefficient of about 94%, and solves the problem of mirror surface protection from powerful influence of pulsing microexplosion products„

- 192 _ ECLIM18: P-3-33

LAra:r-(--Pp-OUCKD .;-:J C'K WAVES :;: LIQUIDS: APPLICATIONS IN npHTi-!ALMr;Lor;Y

L. Drska, K. :!imal, H. Jelinkova, J. Turek, P. Valach

I'"ac . Nucl. ricj., Tech, Univ. of Prague

Analytical studies and numerical simulation of a spark produced by iovv--enorgv lasers in some liquids, with emphasis on shock wave generation and radiation emission in visible and LJV range were undertaken. For numerical studies a one-dimensional Langrangian code with realistic EOS for' liquids and with detailed calculation of the dense low-temperature plasma charac tor:; sties was applied. The Nd:YAG Ias..-r, generating at 1.06 urn and 0.53 um respectively, either in Q-switch or in the mode-locking regime, \-K-IS used to produce sparks in different media. The rat : -,s of the energy in the front of the spark and behind ir and discharge thresholds were estimated. The shock waves produced by spark were detected by a piezoelectric detector-. The spot size in the focus was measured using a CCD camera. The space structure of the spark was recognized. The theoretical and experimental result'- for the shock waves produced in water and solution Ringeri are found to be in good agreement. The experimental system was applied for ophthalmo1ogical purposes. The results of numerical and experimental studies will be used as a part of a microcomputer based expert. system for laser applications in ophthalmology.

- 193 - ECLIM18: P-3-34

ArF LASER ABLATION OF PMMA AND ALUMINIUM A. Jancarek, P. Rejfir, M. Vrbova Faculty of Nuclear Science and Physical Engineering, Technical University of Prague, Bfehova 7, 115 19 Praha 1, Czechoslovakia

The radiation damage may be the cause of specific features of ArF laser etching /I/. The high photon energy (5.4 eV) makes efficient the single photon bond breaking and ionization processes. We report here the results of experiments with the etching of PMMA bulk and Al foil. In order to understand whether the primary ablation of PMMA is due to photochemical or thermal degradation we have measured the etch depth vs fluence for two different sample temperatures (300 K, 364 l<) . The distinction observed was in the range of our experimental errors. Using 30 (xm Al foil in air and the multiple exposures in the focused beam the etch rate was measured to be about 150 nm per 1 3/cm2 (exposure dose) for the fluences from 5 to 50 O/cm^/pulse. The estimated threshold fluence is less than one third of that measured in the case of laser with the longer (355 to 400 nm) wavelength /2/.

1. M.Sekine, 1985 Symposium on VLSI Technology, Digest of technical papers, p.82 2. J.Alspector, R.Contolini, CLEO 1986, Digest of technical papers, p.90

- 194 - ECLIM18: P-3-35

MATERIAL EXPULSION BY TEA CO2 LASER P. Gavrilov, V. Krajicek, M. Vrbova Faculty of Nuclear Science and Physical Engineering, Technical University of Prague, Bfehova 7, 115 19 Praha 1, Czechoslovakia

Efficient surface laser heating of non-metalic materials up to the melting point or to the transition point corresponding to chemical bonds breaking is employed for TEA CO2 laser marking. The understanding of details of beam target interaction is not complete /I/. We monitored the photoacoustic signal in air which was generated by the solid target laser irradiation* The energy density was varied from 0.4 to 20 G/cm2 by focusing 100 ns, 0.2 3 TEA CO2 laser output. The dependences of acoustic signal on the target energy density for different target materials are different allowing us to state the threshold energy density for the material expulsion (e.g. 0.5 3/cm2 for glass and about one order higher for plexi-glass). We are indebted to Dr. P. Sladky for photoacoustic sensor design and fabrication.

1. F.T.Arrecchi, C .Castellini, J.Tredicce, Physical Processes in Laser Materials Interactions (ed. M.Bertolotti), Plenum Press, New York 1983, p.283

- 195 - SOME PHISICAL ANi; METALLURGICAL ASPECTS OF FORMATION OF SOURFACE LAYERS i"U-i METALL SUBSTRATE BY LASER RADIATION

J. Adamka, M. Belko. JI. Styk Slovak Technical University, 917 24 Trnava, Czechoslovakia

The article presents the results of research of interaction between laser radiation and metall substrate. The experiments wore performed with GTE Sylvania 971 continuous CO- l.v.er having 1200 W maximum output power and 10.6 urn wavelength of radiation. The liquid phase was formed on the sourface of metall substrate under the influence of hight power density of laser radiation. The influence of laser radiation, geometry of the liquid phase, phisical and metallurgical processes taking place in the sourface layer are described and explained. Also presented are the results of practical application of interaction between laser radiation and metall substrate at engineering industry.

1. 3. N'azumder, "Laser Heat Treatment", 3.of Metalls,1983 2. M. Belko, "Preparation of working coatings on tool steels" Phil Theses, Technical University, Bratislava, 1984 3. 3. Styk, M. Rrlko, "High-spead steel coating by lasers and electron beams", Bratislava, House of Technology, 1986 4. A.M. Safnnov, "Studies of sctructure and properties of allovs processed by means of laser beams", Proceedings of Int. Conference WELDING 84, Bratislava, House of Technology, ] ' H 4

- 196 - ECL1M1B: P-3-37

CRATERS PHODUCKD BY >fi: :FR IMPACTS IN SOLID TARGETS

M. Kaiiouir: F, '".'••.zet, L. Marty, J.P. Romain I.at^rat.-.ir •• a ' :.r>. r o4ti que et Uetonique. 86034 POITIERS, France.

Para^.ptevir: of craiers wK-p •;;!, wide and shape) in different target materials and their- depenuances on the laser irradiation conditions «r? invest i gate j.

First we haw studied craters size as a function of laser parameter: (pulse duration and focal spot diameter) in the intensity range of 10 ^-* - 10 ^-'- W/cm ^ for pure aluminum targets. In these conditions, the crater is hemispherical and, therefore, the crater depth is chuosen as; the reference parameter. Its value increases with J aser intensity, with pulse duration in the range : ;':•, 1B ns - :'''» n« and with focal spot diameter in the range : 90 pm - 200 ym.

A second set of experiments was performed on different material targets : pure aluminum, aluminum of various hardness (Vickers hardness between 73 to 174), copper, iron, lead and tungsten.

For high intensity laser beam (10 ^ - 10 ^ w/cm 2) the fusion pressure under shock wave seems to be the main parameter for the crater size. For laser intensity below 10 I^W/cm 2 the produced crater is not always hemispherical, particularly for iron and lead, and the crater depth depends on the mechanical properties of the target.

- 197 - .[HE !'\R,\ METERS OF CRYSTAL SPECTROMETERS FOR X-RAY PLASMA DIAGNOSTICS

0, Renuer Institute of Pb . tics, Czeohosl. Acad. Sci,, 180 40 Prague, Czechoslovakia

X—my emission .l'ruin [ i;jsmy pulsed, sources contains extensive inform..! t. i on on the temperature, density, ioni- Zfjtion state, m;iss motion and other characteristics of emitting systems* Instrumental methods commonly used in soft x-ray spoctromctry below 2,5 nm are mostly based on crystal diffraction /l/» The choice of the type and parameters uj" the t.pec t rometer depends on spectral range, dispersion, luminosity, imaging properties and resolving power required /2/« Supposing that the diagnostic data are extracted from the continuum radiation or integrated intensities emitted in spectral lines, modest resolution power is sufficient. On the other hand, when information is to be drawn from the shape of spectral line, resolution at least of the order of 10^- is necessaryB Resolving power of apparatus is given by diffraction properties of crystals and geometrical apparatus smearingj in the latter, the role of source angular size is often principal. The contribution of this factor to broadening the spectral lines may be reduced by use of no—slit focusing spectrometers /3/) asymmetric diffraction from flat crystal / and vertical dispersion variant /5/ of double crystal spectrograph (DCV). The properties of DCV (one- and in special cases two-dimensional spatial resolution, high dispersion, excellent resolving power and relatively high luminosity) are analysed in detail and compared to those of planar and bent crystal scheme. As a representative of curved crystal spectrographs, Johann type is chosen. Its characteristics for linear and planar source are calculated using a method of ray tracing /6/, the widening of single crystal diffraction pattern due to bending is taken into account. Fina- lly, the regions of expedient use of individual spectroscopic schemes are discussed, 1, V.A. Boiko et al., Journ, Sov, Laser Research 6 (1985), 85. 2, B.L. Henke et al., Rev. Sci. Instr. 5^(1983), 131-U 3, Y. Cauchois, C. Bonnelle in Atomic Inner-Shell Pro- cesses (ed. B* Craseman), Academic Press, N, Y, 1975. k* K. Goetz et al., Sov, J. Quant. El, 12(1982), 1170. 5. J. Hrdy, Czech, J. Phys. Bl8(l968), 532. 6. 0. Renner, M, Kopecky, to be presented at Czech. Conf. Phys., Pardubice 1987.

- 198 - ECLIM18: P-3-39 LASER INVESTIGATION OP A SHOCK COMPRESSED SILICON V.B.Mintsev, V.E.Portov, Y.B.Zaporogets Institute of Chemical Physics USSR Academy of Sciences 142432 Chernogolovka, USSR

Physical interpretation of the dynamical experiments in the semiconductor-metal phase transition region is rather indefinite, because of the methodical difficulties, assosiated with the final time of the electromagnetic field diffusion to the sample, contact phenomena and so on. To investigate metal transition of the silicon under powerful shock waves we suggested method, based on the reflection of a laser beam (^.=1,06/^m) from the silicon crystal under dynamical pressures P=10-4o GPa and after it unloading to the helium, formation of the metal-like phase was determined by the sharp increasing of the reflection, because of the appearance of a considerable number of the electrons in the conductivity zone. The measured values of the reflection coefficient of the unloading silicon in dependence on shock wave pressure are presented in the picture. It is seen, that the unloading silicon keeps its reflection pro- i perties R~30% at P =10GPa. There is a sharp jump of the R up to the values 8056 at Pi 15 GPa, The re- P.Cfl* sults of the conductivity measurements in dynamical (curve 1) and static (curve 2) experiments are presented in the picture. We use this values for the estimation of the reflection coefficient (curve 3). It is seen a reasonable agreement with our experiment. Recent data show that there is a silicon metal-like phase at P^ 15 GPa with electron concentration 21 ocentration n^10 cc-cc ' and electricelectricaal conductivity ^ 4 onT'cm .

- 199 - 7r

ECLIM18: 1-7,-P

Mechanism of Conversion of Laser Light into X-Rays

R. F. Schmalz, K. Eidmann, J.Meyer-tcr-Vehn, R. Ramis

Max-Planck-Institut fur Quantenoptik, D-8O46 Garching, FRG

High-Z materials convert intense laser light into X-rays. The efficiency of this conversion is crucial for certain ICF-concepts. Theoretical modelling is necessary in order to understand the mechanism of the conversion. We simulate numerically the interaction of high-power laser light with a plane target consisting of gold. The code is called MULTI and solves 1-D hydrodynamics including flux-limited electron heat conduction and multi-group radiation diffusion. Non-LTE opacities are obtained off-line from the atomic physics package SNOP. The influence of various parameters on the conversion efficiency is studied and compared with experiments. For typical laser intensities around 10l*W/cm2, the gross model which emerges from the code results consists of three elements: First, an (optically thin) corona of a temperature of roughly 1 keV which acts as a converter into X-rays. Second, an (optically thick) Marshak-type radiation heat wave at around 100 eV which is driven by those soft X-rays from the corona which are travelling into the target. This radiation heat wave itself reemits a certain fraction of soft X-rays which add to the conversion rate seen from outside. Third, there is the rather cold, shock- heated material which may be pre-heated by some hard X-rays penetrating the radiation heat wave.

This work was supported in part by the Bundesministerium fur Forschung und Technologie.

- 202 - ECLIM18; 1-3-3

ATOMIC PHYSICS AND SPECTROSCOPY IN X-RAY LASER RESEARCH MODELISATION AND EXPERIMENTS

J.C. Gauthier. J.P. Geindre, P. Monier, C. Chenais-Popovics

Institut d'Electronique Fondamentale. Universite Paris-Sud. 91405 Orsav, and GRECO ILM, Ecole Polytechnique, 91128 Palaiseau. France.

Atomic physics and spectroscopy are o-f paramount importance in the model i sat ion and in the design o-f X-ray laser amplifiers. The great success achieved by Rosen, Matthews and co-workers (1-2) at LLNL in the demonstration o-f a so-ft Xray amplifier using 3s-3p transitions in neon-like selenium has confirmed the usefulness of the isoelectronic sequence of neon in X-rav laser research. These results have led us to explore passible laser action in nearby-Z materials and to look for possible gain increase by external sources of pumping. Resonant photoexcitation of strontium neon-like ions by the radiation of aluminum hydrogen-like ions has been studied both theoretically and experimentally in laser—created plasmas (3). X and XUV spectroscopy have been used as tools to define plasma conditions where photo—pumping may be efficient. The design of targets has been completed bv ablation studies of stontium layers under various experimental conditions. Absorption spectroscopy in a 'two-plasma experiment demonstrates the potential interest of quasi-resonant photoexcitation in neon-like X-ray amplifiers. A detailed col 1isionnal-radiative model, named SPHINX, has been developed. It incorporates five ionic stages centered around the neon-like ion and a few hundreds of excited levels. Atomic properties were included using distorted-wave calculations for collisions and relativistic parametric potential methods for level energies and transition rates. When coupled to a ID hydrocode with detailed atomic physics, it predicts gain contour—curves in good agreement with LLNL results. These tools proved to be a valuable help in the definition of the best plasma conditions for laser action and in developing new diagnostic methods of heavy elements. Extension of this work to nickel-like ions of much higher—Z materials has been made. Preliminary spectroscopic results will be presented at the Conference.

l.M.D. Rosen et.al., Phys. Rev. Letters,54,106(1985). 2. D.L. Matthews et.al., Phys. Rev. Letters,54,110(1985). 3. J.F Wyart et.al., Physica Scripta, under press(1987).

- 203 - ECLIM18: 1-5-4

SOFT X-RAY AMPLIFICATION IN ALUMINIUM RECOMBXNING PLASMA PRODUCED FROM THIN COATED FIBER

A. Carillon, P. Jaegle, G. Jamelot, M. Key , G. Kiehn , A. Klisnick, G. Pert +, S. Ramsden+, S. Rose+, R. Smith+, T. Tomie+, O.Willy

GRECO, I. L. M., Palaiseau """Rutherford Appleton Laboratory

We present the results of amplification measurements performed in recombining aluminium with the laser facilities of Rutherford Laboratory. The target was a seven microns diameter carbon fiber coated with aluminium. The results are compared to the ones obtained in using massive target at Palaiseau.

- 204 - ECLIM18: 1-3-5

PROGRESS IN HYDROGENIC XUV RECOMBINATION LASERS AT THE RUTHERFORD APPLETON LABORATORY

C L S Lewis0, R E Corbett0, M Grande+, M H Key+, G P Wehn*, G J Pert""", C Regan0, S Ramsden4"1", S J Rose+, R Smith*, T Tomle+, 0 Wllll* o Dept of Pure and Applied Physics, Queens University, Belfast, BT7 INN, N Ireland + Central Laser Facility, Rutherford Appleton Lab, Oxon 0X11 OQJC, England * Physics Dept, Imperial College, London SW7 2BZ ++ Dept of Applied Physics, University of Hull, Hull HU6 7RX

Using novel line focussing optics six beams of the VULCAN laser at the Central Laser Facility have been used to quasl-symmetrlcally Irradiate 7um diaaeter carbon fibres over lengths of several centimetres at Incident lrradlances of > 10l* Wcm^ In pulses of < lOOps at O.53gm. During the subsequent fibre expansion and recomblnlng phase time resolving XUV spectrometers have been used to measure axial amplification of the Balmer-alpha transitions in both hydrogenic carbon (> - 182 S and o - 3-4cm~^) and hydrogenlc fluorine, from LiF coated fibres, (J - 81H and a - 2-3 cm"1).

Progress in our understanding of the hydrogenlc recombination scheme will be reported and in particular the difficulties associated with lsoelectronlcally scaling the scheme to the biologically Interesting "water-window" at 23-441 will be assessed.

- 205 - ECLIM18: 1-3-6

NON-EQUILIBRIUM GENERATION OF HIGH-PRESSURE PLASMA WITH A CW CO2 LASER Yu.P. Rayzer Institute of Mechanical Problems, Moscow

- 206 - EIUM18: 0-4-

SiMlii r,,-.-".> r., •>.•!-:A- AJj;J C'*-'J,|^A1 :r-H ADOlvGRAPHY OF CAVITIES .'if A'ED Bv ^ - t».44 JJIHJ LASER LUGHT

i.B Foic'es"', R. S»tjc:!, Chen Shisheng , K. Eidimann, R.F. Schmalz G.D Isa^'ros, S.

Max-fjJj^ck-lnstitut fur Quantenoptik Garching, Fed. Rep. of Germany

Gold cavity targele ive»x- irradiated by A - 0.44 jjm laser light at • 2.6 x 10 W/cm2. The outward motion of the cavity wall was investigated by simultaneous oplicaS and x-ray shadow- graph y. The wall motion is attributed lo the pressure generated by an ablative heat wave, driven by the soft x-rays in the cavity. The observed transparency of the cavities for the backlighting x-rays allowed us to determine ihe decaying density profile of the moving cavity by Abel inversion. The observed law density of the wall is explained by fragmentation cf the condensed wall material.

Permanent address: 1) Central Research Institute for Physics, H-1525 Budapest, Hungary. 2) Shanghai Institute of Optics and Fine Mechanics, Shanghai, People's Republic of China.

This work was supported in part by the Commission of the Euro- pean Communities in the framework of the Association Euratom/IPP.

- 207 - ECLIM18; 0-4-2

COMPARATIVE STUDY OF X-RAY GENERATION iN A CAVITY HEATED BY 1.3 pm OR 0.44 pm LASER LIGHT

S. Sakabe1^, R. Sigel, G.D. Tsakiris, I. Foldes , P. Herrmann

Max-Planck-lnstitut fur Quantenoptik D-8046 Garching, Fed. Rep. of Germany

Spherical, thin-walled gold cavities (250 to 1000 pm diameter) were heated by 300 ps laser pulses with either 1.3 pm or 0.44 pm wavelength. Laser light absorption, x-ray generation and expansion of the cavity was investigated by an Ulbricht box, by x-ray spectroscopy, by pinhole photography and by time- resolved shadowgraphy, respectively. Laser light of K - 0.44 pm wavelength is not only more effective in cavity heating, but also more suitable to generate thermal x-ray radiation in an empty volume.

On leave from: 1) Institute of Laser Engineering, Osaka University, Japan. 2) Central Research Institute of Physics, Budapest, Hungary.

This work was supported in part by the Commission of the Euro- pean Communities in the framework of the Association Euratom/IPP.

- 208 - ECLIM18: D-4.7

THE THEORY OP ACTIVE MEDIA IN EXCIMER LASERS A. G. Molchanov P.N.Lebedev Physical Institute, Ac.Sci., Leninsky prospect 53, Moscow 117924, USSR

The main principles of the excimer laser theory are presented. The theory of electric discharge-excited lasers is based on the Boltzraann equation for electrons, which allows one to calculate rate constants and the energy distribution between components of the active media. It also includes calculations of the ionization instability, which determines the maximum admissible power input. A simple method has been proposed to calculate energy deposition profiles in the diluent gas of e-beam pumped lasers. It uses scaling of the deposition curves. The theory is applied to calculations of the active media properties in some excimer lasers. The detailed theory of KrP-laser active medium excited by a beam of fast electrons is given. To take into account the influence of the amplified spontaneous emission (ASE) on the parameters of wide-aperture optical amplifiers we have developed a simple method for a numerical solution of the radiation transfer equation. There is a noticeable influence of ASE on the parameters of wide- aperture amplifiers to be used in the laser fusion. The numerical calculation has been made for wide-aperture e-beam pumped KrP-amplifiers including three-dimensional ASE and diffuse reflection from side walls of a cavity. It is shown that the efficiency of KrP-amplifiers can reach about 3% with gain more than 10, even if the ratio of output window diameter to the amplifier length is around 0.6. In this case, however, the input flux should be about half of the saturated flux. Host promising are Kr:F_ mixtures with relative concentration of fluorine 0.3-6.5%, total gas pressure 0.8 atm, and power deposition rates 0.4-0.6 MW/cm .

1. Yu.V.Afanasiev, N.G.Basov, V.A.Danilychev, A. G.Molcha- nov, "Laser fusion and driver problem", Preprint PIAN N 33, p.1-69 (1984). 2. A.G.Molchanov. Trudy PIAN, v.171, p.54-127 (1986).

- 209 - URA CODED APERTURE CAMERAS WITH SPECTRAL OR TOMOGRPHICAL RESOLUTION FOR LASER IMP'.ODED PLASMA DIAGNOSTICS M. Yamanaka, Y.-W. Chen, H. Miyai, N. Miyanaga, H. Niki, T. Yamanaka, Y. Izawa, and C. Yamanaka Insutitute of Laser Engineering, Osaka University, Yamada-Oka, Suita, Osaka 565, Japan and S. Tamura Department of Information and Computer Science, Faculty of Engineering Science, Osaka University, Toyonaka, Osaka 560, Japan In order to obtain a spectrally resolved X-ray image and a three-dimensional compressed-core X-ray image in the inertial confinement fusion experiments, a Ross-filtered URA coded aperture camera (Ross-URA) and a computed tomograph using two URA coded aperture cameras (URA-CT), respectively, have been developed. For the Ross-URA, we have made a Ross-filtered URA pattern (15x17 m-sequence) using a combination of Ni and Cu thin foils which is to get the X-ray spectral resolution between 8.3 KeV and 9.0 KeV. This Ross-URA camera was successfully appiled to have a GEKKO XII laser imploded plasma image in the spectral range of 8.3 ~9.0 KeV. For the URA-CT, we successfully tried to reconstruct a three-dimensional laser-imploded core image from encoded X-ray images using two orthogonal URA cameras with 31x33 m-sequence patterns. The three- dimensional compressed core image reconstructed was compared with an X-ray pinhole camera image, and we observed a fairly good agreement between them. THe computer simulation results on the URA-CT are presented The potential applicabilities of Ross-URA and URA-CT for the laser imploded plasma diagnostics will be discussed.

- 210 - ECLIM18: 0-4-5 Characterisation and Optimisation of a Laser Generated Plasma Source of Soft X-rays for Biological Imaging.

A.M.Rogoygki C.P.Hills A.G.Michette P.Charalambous

Physics Dept.,King's College

The Strand, London WC2R 2IS. U.K.

Laser-generated plasmas have for some time been seen as a powerful laboratory based source of soft X-rays. Recently, there has been much interest in such sources to generate line free coiitinua for applications such as microlithography and EXAFS. In contrast, recent- work carried out at King's College has been biased towards the creation and optimisation of a strong line source for uses in biological imaging. Of particular interest to biologists is the spectral region between 280eV and 530eV, the so called 'water window' where elements that constitute much of biological material, such as carbon are highly absorptive while water is at its most transmissive. This promises the possibility of imaging 'wet' biological specimens.

Using a Nd:YAG laser producing a 0.5J pulse lasting 8ns, power densities of up to

~3xlO12 W/crrv are generated on target. A grazing incidence grating spectrometer in conjunction with various X-ray diode arrays enabled flux and spectral measurements of the source to be made. A pin-hole camera in conjuction with K-edge filters provided details about the shape and size of the emitting regions. Extensive characterisation studies have been carried out including the effects on X-ray flux and spectral quality of different focusing conditions, laser wavelength (1/im and 0.53/zm), and Z-dependance. Further studies include angular distribution measurements of X-ray flux and the effects on these distributions by parameters such as focusing conditions, target damage and differing target materials. Other problems such as debris are discussed with experimental data on the parameters effecting the production of debris. Finally, the applications of the optimised source will be discussed with some examples.

- 211 - ECLIM18: 0-4-6 Characterisation of KrF Laser-Plasma X-ray Source in the 280eV-530eV Photon Energy Range

A.M.Rogoyski C.P.Hills A.G.Michette Physics Department, King's College The Strand, london WC2R 2IS. U.K.

ICE Turcu F O'Neill U Zammit laser Division, SERC Rutherford Appleton laboratory Chilton, Didcot, Oxon 0X11 OQX, U.K.

Y Al-Hadithi and R W Eason Physics Department, Essex University Wivenhoe Park, Colchester CO4 JSQ U.K.

Recent interest in soft X-ray contact microscopy has lead to the demand for a high brightness laboratory based source of soft X-rays. To maximise the image qualities it is necessary to carefully characterise such sources. Using the Rutherford Appleton Laboratory Central Laser Facility KrF laser (SPRITE) capable of producing up to 200J in a 60 us pulse at a wavelength of 249nm, characterisation of carbon, tungsten and gold targets has been carried out at power densities of between 2x10'' W/cm2 and 4xl0l?l W/cm-. A grazing incidence grating spectrometer was used to record carbon spectra in the energy regions between 280eV and 530eV, the 'water window'. Absolute measurements of X-ray production in this range were made using filtered X-ray diode detectors. The conversion efficiencies of incident laser light to X-rays were thus measured as functions of target irradiance. For carbon targets a peak conversion efficiency of 8.5% was recorded at an irradiance of 1.2xlO12 W/cm2 . Similarly for gold and tungsten peak conversion was measured to be 24??. at 2xl212 W/cm2.

- 212 - FRIDAY

MAY 8 ECLIM18: R-5-1

Laser Heated Cavities+ G. D. TSAKIRIS, R. SlGEL, K. EIDMANN, I.B. FOLDES*, P. HERRMANN, R. PAKULA, S. SAKABE**, S. WITKOWSKI Max-Planck-Institut fur Quantenoptik, D-8046 Garching, F. R. G. The conversion of the laser energy into soft x-rays and its thermalization and confinement inside a closed geometry target has been investigated experimentally and theoretically. Using the ASTERDC-III laser system spherical gold cavities (0.3 - 1.0 mm in diameter) were heated with an average intensity of 1012 to 3 • 1013Wycm2. A systematic study has been performed at two different wavelentghs of A = 1.3/j,m[lu>) and A = 0.44/xm(3w). Various diagnostics provide information about the laser light absorption, the dynamic behavior of the expanding shell and the temperature variation of the inner cavity wall. Particular emphasis has been given to the study of the spectra emanating from the interior of the cavity. The experimental results are compared with the predictions of a model based on the diffusive loss of radiation into the cavity wall and found in good agreement. In addition, the post- processing atomic physics code HOLRAD reproduces the main features of the experimentally obtained spectra. The heating experiments showed that more favorable conditions can be achieved at A = 0.44fim and effects like plasma filling and hole closure can be avoided. A brightness temperature of 192 eV has been recently achieved in a joint experiment with ILE/Osaka using more energetic laser pulses1. It is concluded that the laser-plasma interaction processes at high intensity may pose a limitation for generating intense thermal radiation in a cavity. 1. T. Mochizuki et al. IAEA Conference on Plasma Physics and Con- trolled Nuclear Fusion Research, Kyoto, Japan, 13-20 Nov. 1986, Pa- per IAEA-CN-47/B-I-3 permanent address: * Central Research Institute for Physics, Budapest, Hungary ** Institute of Laser Engineering, Osaka University, Japan + This work was supported in part by the Commission of the European Communities in the framework of the Association Euratom/IPP.

- 215 - ECLIM18: R-5-2

NUMERICAL SIMULATION OF IMPLODING THIN SHELLS J.H. Gardner NRL

- 216 - ECLIM18: R-5-3

Extending X-ray Lasing to Shorter Wavelength D. C. Eder, M. D. Rosen, R. A. London, and S. Maxon University of California Lawrence Livermore National Laboratory Livermore, California 94550 U.S.A.

The demonstration of x-ray lasing and significant gain at 206 and 209 A in neon-like selenium has provided incentive to extend x-ray lasing to shorter wavelength. A wavelength region of particular interest is between 22 and 44 A called the "water window." In this wavelength region, there is maximum contrast between carbon or nitrogen and water allowing for the possibility of creating holograms of cells in a water medium. We will discuss three approaches to this goal of lasing at wavelengths less than 44 A. The transition corresponding to 206 A in neon-like selenium is at 40 A for 1 4 neon-like gadolinium. The power requirements scale as X making this approach costly. However, the use of correcting mirrors or special target designs that reduce refraction could reduce the power requirements- An alternative approach 2 •3 is lasing in a recombining aluminum plasma where the n=3 to n=2 transition in hydrogen-like aluminum is at 39 A. To obtain large gain the aluminum strip must be completely ionized before there is significant hydrodynamic expansion of the target. This requires that the duration of the driving laser pulse be < 20 psec. A third approach to achieving lasing below 44 A is a nickel-like rhenium system. The kinetics of the nickel-like systems are similar to those of the neon-like system but the power requirements are less severe. The predicted low gains require the use of mirrors to allow for multiple passes through the lasing medium.

1. M. D. Rosen, R. A. London, and P. L. Hagelstein, LLNL report, UCRL-95137. . 2. G. Pert, Plasma Physics, 27, 1427 (1985). 3. D. C. Eder and M. D. Rosen, Bull. Am. Phys. Soc, 32. 1458 (1986). 4. S. Maxon, P. Hagelstein, J. Scofield, and Y. Lee, J. Appl. Phys. 52, 293 (1986).

*Work performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under contract number H-7405-ENG-48.

_ 217 - ECLIM18: R-6-1

PROGRESS ON THE PARTICLE BEAM FUSION ACCELERATOR II FOR LIGHT ION FUSION*

J. P. VanDevender Pulsed Power Sciences Sandia National Laboratories Albuquerque, New Mexico 87185 USA

ABSTRACT

High powered lasers have provided the principal experimental tools for research on high-density high-temperature natter. In parallel with the development of this branch of plasma physics, high powered particle beam drivers are being developed to provide roegajoules of energy at 14 2 10 watts/cm for Inertial Confinement Fusion. Particle Beam Fusion Accelerator II (PBFA II) at Sandia National Laboratories is the largest in the series of particle beam drivers and the first with the potential of achieving the necessary energy and power density required for igniting thermonuclear fuel in the laboratory. PBFA II is a series of experiments in pulsed power, power flow, ion sources, lithium ion beam generation, beat transport, beam focussing, radiation physics and implosion hydrodynamics. If these challenging experiments are successfully completed, then thermonuclear fuel may be ignited in the laboratory for the first time. Because of the large number of research items in series, the risk is very high and the experiments will require many years of intensive effort. On December 15, 1985, PBFA II construction was completed and the accelerator was activated. Since that time, the pulsed power has been developed and major experiments in power flow and ion sources have been conducted. Preliminary experiments on beam generation have also been conducted. The accelerator is currently operating and providing one fully diagnosed experiment each week at 100% of its rated energy storage. The PBFA II program and the results to date with this technology will be presented. The advantages and disadvantages of using intense ion beams, which penetrate matter to heat it uniformly, will be briefly surveyed.

*This work is supported by the U. S. Department of Energy under Contract DE-AC04-76DP00789.

- 219 - ECLIM18; R-6-2 "Physics of High-Power Light-Ion-Bean—Target Interactions" K. Yatsui, Y. Shinotori, Y. Araki, K. Masugata and S. Kawata Laboratory of Bean Technology, The Technological University of Nagaoka, Nagaoka, Niigata 940-21, Japan Abstract Experimental and theoretical studies are presented on the physics of an intense pulsed light-ion bean interaction with targets.' Experimentally, following articles will be discussed; I) development of self-magnetically insulated "Plasaa-Focus Diode" (PFD), 2) construction of new pulse-power Machine "ETIGO-II" and pulse-coapression experiment, 3) observation of ablation process in ion-beaa-target interaction by backlighting technique, and 4) tine-resolved measurement of energy and species of pulsed ion bean, and so on. Regarding the itea I), we have found the PFD produces a very high ion-current density coapared to any other diodes developed so far. Concerning the itea 2), we have operated new machine "ETIGO-II" froa last March, which specifically produces the pulse-power output of 3 MV, 460 kA, 50 ns, 1.4 TW, 70 kJ. Using plasaa- erosion opening switch, we have carried out pulse-coapression experiaent. For the itea 3), we have succeeded in the measurement of the bean-target interaction with backlighting taechnique newly developed. The ablation pressure has been observed to be ~ 1.6 x 103 bar at the bean-power density of ~~ 2.4 GW/cm2 for "thick" target for proton bean with the energy of ~ 1 MV. Regarding the itea 4), we have succeeded in the tiae- resolved measurement of energy and species of the pulsed ion beaa by use of MicroChannel plate iaage-intensifier. Theoretically, we have developed a 2.5-diaensional particle-in-cell computer simulation code named PCSKfK. Using this code, we have studied the motion of particles in the acceleration gap, focusing and transport of the ion beaa in a vacuum. Furthermore, the motion of electrons has been successfully clarified in the PFD, which has been found to be in a reasonable agreement with the experiaent. Reference 1) K. Yatsui et al.: Proc. 2nd Int'l Top. Syap. on ICF Res. by High-Power Particle Beaas, Nagaoka, 1986, ed. K. Yatsui (Lab. Beaa Tech, Tech. Univ. Nagaoka) 1 (1986). - 220 - ECLIM18; R-6-3

OPTIMIZATION OF TARGET FOR ICF AND TARGET GAIN

Keishiro Wiu Department Of Energy Sciences, The Graduate School at IKagatsuta Tokyo Institute of Technology, Midori—ku, Yokohama 227. Japan

In order to obtain the practical amount of fusion energy by inertial confinement fusion (ICF), the fuel in the target must be heated and compressed. When the fusion output energy of 3GJ is expected to be obtained from a.target, the number of DT reactions in a target must be of order of 10 . If we assume that the burn fraction of the fuel is f=20%, then the fu^l mass in a target is required to be M =20mg. In order that the burn fraction of the fuel reaches a value or more than 20%, the fuel temperature must be T.>4keV and the fusion parameter is required to be jR>4g/cm , which lean's to fjlQQOf . The compression of the fuel to this high density is especially difficult to be realized in the small target. The adiabatic compression is proposed to achieve this high density. To heat to T.=4keV and to compress-to J=2000f of the DT fuel, the fuel pressure becomes of order of 10 Pa at last. Usually the pusher in the target expands with the increasing pressure, and the pressure saturates at the level of 10 Pa. Accordingly by the ordinary adiabatic compression method, it is impossible to achieve the high compression of the fuel technically. Fortunately, the process of implosion of the fuel is carried out nearly isentropically. In the early stage of the implosion, the fuel is strongly accelerated with an acceleration of 10 cm/s , provided that the initial target radius is 6mm. There is a possibility that shock waves travel across the fuel layer in this early stage of implosion, depending on the way how the pusher pressure increases. In the later stage of implosion, however, the fuel is decelerated strongly but gradually without a shock wave near the target centre and the momentum changes to the impulse which leads to the high pressure with a short time interval of deceleration. The target has to have the tamper layer to suppress the energy loss due to blowoff. The driver is required to deposit the energy exclussively in the pusher layer. The target with a larger radius gives the larger implosion velocity of the fuel. The radius is decided from the point of view of the uniform (or stable) implosion. If we assume that the driver is proton beams. Then for the target with the radius of r =6mm, the tamper (lead) mass of Mp,=150mg (the initial thickness is » .=20.5^m), the pusher (aluminium) mass of MA1=191n£ (J** =156pm) and the fuel (DT) mass of Mp^S^ing (JjjT= 27.6/mT, the driver witith tthhe bbea m energy off E =8MJ8MJ, tthhe pulsl e widtidhh off t =30n30 s andd thhe particle energy of e =5.1MeV extracts the fusion output energy of E_ =2.46GJ and the targe? gain is G=410.

- 221 -III ECLIM18: 1-4-1

SPECTRAL LINE PROFILE MEASUREMENTS ON LASER PRODUCED PLASMA H.R. Griem The University of Maryland

- 223 - D£S!C.\" J.'D CHARACTERIZATION FOR ABSOLUTE X-RAY S?EC?r:CMETKY IN THE 100 - 10 000 EV REGION

An Ab3Li. .!: Frc-pared for a Presentation at the 18; h European Conference on Laser interaction with Hatter Prague May 4-8, 1987

Burton L. Henke Center for X-kay Optics University of California f vuence Berkeley Laboratory 1 Cyc iouron Road Forkeley,' C.difornia 94720

ABSTRACT

Reviewed here are the design and characterization procedures used ii: ur program for developing absolute x-ray spectrometry in the 100-3 0 000 eV region. Described are the selection and experimental calibration of the x-ray filters, mirror monochromators, crystal/multilayer analyzers, and the photographic (time integrating) and photoelectric (time resolving) position-sensitive detectors. Analytical response functions have been derived that characterize the ciiergy dependence of the mirror and crystal/multilayer reflectivities -jMit of the photographic film and photocathode sensitivities. These response functions permit rapid, small-computer reduction of the experimental spectra to absolute spectra (measured in photons per tearadian from the source for radiative transitions at indicated photon o'-crgies). Our x-ray spectrographic systems are being applied to the diagnostics of pulsed, high temperature plasma sources in laser fusion and x-ray laser research.

- 224 - ECLIM18: 1-4-3 SOME RECENT CONCEPTS IN ICF NEUTRON DIAGNOSTICS G.H. Miley University of Illinois at Urbana-Champaign

- 225 - ECLIM18: 1-4-4

LASER PLASMA APPLICATION FOR LASER DEVELOPMENT

V.BO Fedorov Institute of General Physics of USSR Academy of Sciences, Moscow, USSR

Laser plasma research, greatly stimulated by the development of high-power laser engineering, gives, in its turn, a backward impact on laser engineering itself. A brief review of laser plasma application in physical experiment is presented starting from the electrical discharge launching by means of optical break-down for the purpose of electrooptical Q-switches control in lasers. Application of laser plasma for control of laser radiation parameters (development of radiation pulse fronts, spatial filtration of radiation and others) is discussed. A new stage in laser plasma application for laser engineering is associated with the development of plasma mirror lasers. The history of the problem is presented. It is noted that in various laser active media plasma mirrors might function not only as optical resonator mirrors, but also as optical shutter and nonlinear element for mode locking. New results on neodymium lasers with plasma mirrors are presented. Ultrashort pulse generation is for the first time esternally initiated in this laser. An effect of low-threshold stimulated Mandelstam-Brillouin scattering (SMBS) reflection is detected on a plasma mirror with the reflected pulses being far shorter than the incident ones. The dynamics of generation of ultrashort picosecond pulses from neodymium laser with plasma mirror is experimentally studied starting from the initiation instant. A smooth quasicontinuous generation with a narrow spectrum, not earlier reported, is also obtained in neodymium laser with plasma mirror. The use of laser plasma in laser engineering is currently increasing and promises interesting applications enabling in some cases to change high-cost and complicated optics by plasma optic elements.

- 226 - ECLIM18: 1-4-5

I'V laser plasma and it's application to laser pulse switching

Lou Shanghai Institute of Optics and Pine Mechanics Acacicrnia Sinica, PO Box 8211, Shanghai, P.R.C.

Abstract The characteristics of the laser plasma created by hiqh intensity UV excimer laser were investigated. The UV laser plasma was used as a switch for control the laser pulse duration for the first ti:ne. An X-ray preionised XeCl laser pulse can be changed from 10 to 85 ns , this technique is useful for many applications of excimer laser with vari3«s pulse duration.

* paper submitted to 18th ECLIM, 4-3 May I987, Pra<*ue, Czechoslova iia.

_ 227 - ECLIM18: 1-4-6

VAPORIZATION AND RECONDENSATION IN LASER DRIVEN REACTORS: THE LIMITING ISSUES AND UNCERTAINTIES* William J. Hogan, Charles D. Orth Lawrence Livermore National Laboratory Livermore, California ABSTRACT

To date, all economically reasonable designs for laser fusion reactors have relied upon some type of self renewing first wall which will partly vaporize with each fusion pulse. The physics of isochoric vaporization and subsequent condensation will be discussed. Model calculations for several first wall materials are presented. Phenomenological uncertainties will be identified.

*Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48.

- 228 - INDEX TO AUTHORS Ab&zekhov M.M. 127 Carillon A. 204 Abdupataev R. 165 Cartwright D.C. 160 Acopian E.A. 095 Caruso A. 099 Adamka J. 196 Cavenago M. 094 Afanasiev Yu.V. 084,186 Cesarz T. 148 Ahedo E. 117 Charalambous P. 211 Al-Hadithi Y. 212 Chausbansky S.A. 171 Alejaldre C. 123 Chebotareva E.I. 126 Aleshin A.I. 126 Chen Y.-W. 210 Apte P. 150 Chen Shisheng 207 Arakj Y. 220 Chen Zezim 067,173 Aririengaud M. 089,108 Chenais-Popovics C. 140 125,153 203 Arras C. 089,108 Chernovs E.A. 069 125,153 Chevokin V.K. 177 Arendzikowski R. 106 Chumakov A.I. 164 Attwood D. 216 Chvo^ka M. 163 Badziak J. 133 Cicchitelli L. 045 Balmer J.E. 141,178 Coe S. 136 Banfi G.P. 067 Coggeshall S.V. 160 Barkhudarov E.M. 131 Cole A.J. 149,150 Barrero A. 078 Corbett R.E. 138,205 Basov I.G. 039,132,143 Cornolti P. 067 161,183,188 Cottet P. 135,137,197 Coutts G.A. 047,062,063 Bassett D. 189 Cunningham P.P. 172,179 066, 107 Danilov A.E. 189 Barr H.C. 124,136 Danilova G.V. 188 Basylev B.I. 062,063 Danilychev V.A. 161 Bedilov M.R. 086 Dashevsky B.E. 165 177 Belko M. Deha I. 120 Belousov If.I. 196 Demchenko I.I. 188 Belovolov M.I. 189 Denus S. 100,106,110 Benc I. 127 132,133,147 Berendeev S.A, 176 Dinguirard J.P. 088,089 Berge L. 192 108,125 089,108 153 125,153 Djaoui A. Bergmann A. 070 150 Beysenbaeva H.E. 165 Dragila R. 061,101 Bitzan P. 106 Drake R.P. Blair L.S. Drska L. 081 114 160 ,082,106 Bobashev S.V. 144 Bormaud G. 064 Dubik A. 145 193,201 Borovik P.I, 086 ,146,147 Boyd T.J.M, 047,062 Dzwigalski D. 148 063 Eason R.W. 133 Briand J. 089,108,125 Eder D.C. Eidmann K. 092 150,212 153 217 Brown D, 149 Brunner W. 102 Elenin G.G. ,154,202 Bushman A.V. 187 Epatko I.V. 207,215 Bykowskij I.E. 147 Erokhin A.A. 098 Campbell E.M. 113 Erokhin I.S. 162 Campbell R.I. 172 Evans R.G.- 182 Capjack C.E. 105 Pabre E. 049,073 066 055 - 229 - FaItTO R. 135,, 1 37 Hull or i'>. 041 Fadeev A.D. 07 3 Ilir C.V. 096 ,183 ,184 Far&l p.. 051 ,135, 137 Isakov V.A. 186 Farny J. 085, 106 ,133, 182 Islava ¥:, 1 07, 1 74 Fedorov V.E. 166, 167,168 Iwanc'W 7.J. 147 22 6 Izav:& Y. 210 Fedcse.jevt- R. 105, 1 57 J&tgle P. 204 Fedotov 2.1. 142 ,14.?, 170 Jackson C.L. 150 1 7 I,189 Jamelot G. 204 Feigir >>.Ivi. OG'i Jar.carek A. 1 94 Fiedorcwics H. 106,110, 1 80 Janulewic? K. 133 Fo]dep I. 207,708, 215 Jerccka R. 193 Fomerkov l.V. 1 66, 1 6 i ,168 Jelinkova V. 193 Fortter E. 1 42 Jensen F.J. 159

Fortov V.E. 116,127, ! . . • Jesiak K. 106,110 187, 199 Kg gar, D.TvT. 192 Preenkel E.G. 1 7 9 Kalal f;.. 07 9 Foremen L. 160 Ksla&hi'.ikov M.P. 142,143 C-airaly E.G. 03 9,044,077 Ka ran i c IT e va ;"'. A. 165 126, 132 Karpcv V.Ya. 1 84 ,188 Gardner G.A. 04 7 Ka.r1.tuner 7.3. 04 8 ,107 Gavithier J.C. 140,203 118,174 Gavrilov E.M. 075 Kaskova C.I. 086 ,08. Gaviilov P. 1 99 Ke&yanov Yi;./>. 151 Geindre J.P. 140,20 7 Kev:ata 2. 22 0 Gelashviii G.V. 131 Key M.H. 058,149 Giulietti A. 067,107, 124 204 ,205 Giulietti D. 067 Klnn'r.ibullaev P.K 165 Giver. 17. 1 36 KhEichiyan K.A. 084 ,186 God.z: \i 146 Kraritonov V.V. 189,190 Gcets K. 1 /-...-.' Khimicb A.V. 07 2 GoIdman 3.R. 1 52 Kieffer J.C. 089,108 Gold &lore P.D. 160 125,153 Goldeworthy M.P m 04 5 Keihr G.P. 204 ,205 Gomes A. 089, 108,125, 153 Kilkemy J.D. 138 Goncharov S.F. 174 Kiyelev A.E. 07 7 Grande M. 136,139,205 Kliarick A. 090,204 Grierr; H.R. 22 3 Kcresheve E.R. 191 GrJshuirjr P.A. 189 Kern G. 142 Gromov E.M. 074 Kocteckj J. 133 Guennou H. 090, 109 Kctelnikcv S.S. 175 Gun.beridze G. G. 131 Krat";icek V. 195 Gupta P.D. 157 Kralikova P. 163 Guakov G.Yu. 143,183, 184 Kraaa J. 163 188 Krasj/uk I.K. 127,128 Hall T.A. 150 129 ,130 Hallouin 137, 197 151 ,187 Hair; a 1 K. 193,201 Kristal R. 160 HanIon J.A. 160 Krousky E. 176 Hav.tr A. 160 Kryukov P.P. 187 Hei] P. 130 Ku&nierf J. 146 Henke E.L. 224 Kv.rdyi.mo-v S.P. 097.,098 Herrmann P. 208,215 sx'U.T'j^ 3 HE. E • o • 098 Hern'cch V. 163 Kuzretscv A.V. 127 HiDlc C.P. 211, 212 Lampart R.W. 141 Hogar. W.J. 228 La2"f-:en J.T. 057 Hora V.. 045 La&ke L. 163

- 2 30 - Lsv&l G. 1 1 o UiCj I''.- ".. 1'. • 0'. Lazsrcvfi E.V. 1 26 I.io c 1 a. c c 1 b. * r-\ r Let>o I.G. 08G, ir-6, V.-5 l\rcz W. ! 'J1;. 189, 19? I:':: 1 ser V. 04 1 , K. • V Lee R.W. 138 MM j dak W. Lee Y.T. 105 L?J.£.:.il J. 1 63,2 01 Levanev E.I. 07 6 Nsgrabs S. 106 , 1 80 L e v k o v s k y A . A . 096. 183 Katarcv C.Y 169 18A Nee A.L. 1.P9 Lev;is C.L.S. 138, 179 Ng A. 104 205 Nicolas J.A. a 122 Lin;pouch J. 080, 081 , 106 ITiki H. 21 0 Lirdl J.D. 115 Kikki ter.kc T" 191 Li ska Ii. 082 NiLJ K. 221 Litvak A.G. 069, 071 riocera L. 067 ,068 Loijcer G. 080, 1 06,201 Kerrey£ P. 149 Loudon R.A. 217 i:otci;tt E. 1"7? Lu c c h e s J IVJ . 067 Offentergor A * A • 157 Luther-Davies E. 101 o'Kfeill D. 138 Macsur M. 133 O'Neill P. 158,212 Maddever A. 101 Orth Ch.D. 22 8 Makcwyki J. 146 Owt-ik J. 146•,147 ,148 Meksichv.k A.M. 142 Pakula F. 215 Marchand R. 105 Part K.C. 103 Marczak J. 147 Paryd P. 110 Mariy L. 137, 197 Psrys P. 133 •* r- r • Macek K. 163 Pashinin P. P 127 , i ^O Masugata K. 220 *129 ,130 ,151 Ma.tevoc&ian G.G. 095 162 ,169 ,187 Maxcrj S. 217 Pav/lov/icz W • 1 06,110 May R.G. 170 Pellani R. 065 Mazur flf.Yu. 171 Perez -Sabor id M. 078 McCrory R.L. 040 Perinove V. 059 MeLeod J. 160 Perl G.J. 204 ,205 Mead W.C. 160 Pesme D. 064.,125 Meyer-Ter-Vehn J. 091, 202 Pesroe E. 118 Michaelis M.M. 172 Pestov E.G. 121 Micbette A.G. 211, 212 Pina L. 106 ,176.,201 Mika J. 178 Piotreeski J. 147 Mikbailov A.P. 0 97, 098 Pisarchik T 132 Mikheilov Yu.A. 142, 143 Podvya2.r.i k ov V• Am 177 171 Polak S. 16^ In" ley G.H. 22 5 Popil R. 157 M±ni ri V.P. 187 Potapov A.B • 098 Minko L.Ya. 164 Prokbii'deev A.V. 177 Mintsev V.P. 199 Prckborov A .M. 1 °7 ,128 Mii'ouov V.A. 072 -1 " A Mishchenko T.V. 184, 188 1 2 9, 1 -•'0, ,1 41 Mishkin A. A. 123 1 6 6, 16/, 1 68 Miyai H. 210 177, 187 Mdyanage N. 210 Qihorig Lou 22 7 Mciseev C.8. 04 9 Quemener Y. 089 ,108, 125 Molcbsu'ov A.G. 2 0 9 153 Moller C. 100 Rakova E.I. 071 Monier P. 140, 203 Ra.rr.ain J.P. 135 Montes C. 065 Ra.ir:is R. 093, 202 Mcntierth I.M. 160 Rainnderj V. 204, 205

- 211 - Ray R.S. 045 Shmaenok L.A. 144 Rayzer Yu.P. 206 Shpilrain E.E 192 Reagan. C. 204 Shumsky S.A. 042,119 Regan C. 205 Shvets V.F. 075 Rejfir P. 194 Sigel R. 207,208,215 .Renner 0. 176,198 Sikoreki Z. 133 Riley D. 136 Singh D.P. 050 Roberts B. 060 Singh R. 050 Robertson E. 138 Skala J. 163 Rede A.V. 142,143 Skljzkcv G.V. 039,142,143 Rogoyski A.M. 211,212 147,170,171 Rohlena K. 163 189,192 Remain J.P. 137,197 Smelkov A.I. 170 Romanov G.S. 086,087 Smith A. 061 Rose S.J. 136,150 Smith R. 204,205 204,205 Sotsky E.K. 076 Rosen M.D. 217 Spiridonov V. A. 166 Rosocha L.A. 160 Stanchits L.K 086 Rozanov V.B. 039,042,080 Stening R.J. 045 086,119,126 Stepanov K.L. 086,087 143,175,183 Stoll I. 079 184,188,189 Styk J. 196 192 Subbotin V.I. 189 Rubenchik A.M. 075 Suchanska R. 134 Rumsby P.T. 136 Sureau A. 090,109 Rupasov A.A. 132 Sylvestre N. 118 Saadat S. 138 Szichman H. 045 Sabitov M.C. 165 Szymanski A. 148 Sagdeev R.Z. 049 Ta^'ima T. 046,094 Sakabe S. 208,215 Taktakishvill M.I. 131 Salomaa R.E. 048,118 Talanov V.I. 074 Samarskii A.A. 098,188 Tamura S. 210 Sanmartin J.R. 117,122 Teterev A.V. 086 Santiago J. 157 Tikhonov A.G. 142 Sanz J. 078,122 Titov S.N. 126 Sarkisov G.S. 132 Tomie T. 204,205 Sartory A.V. 143 Tregin N. HO Sarzynski A. 145 Tsakiria G.D. 092,154,207 Scblegel Th. 102 208,215 Schmalz R.P. 152,154 Tsui Y.Y. 157 202,207 Turcu I.C.E. 212 Schmiedberger J. 163 Turek C. 193 Schnabl H. 070 Urbanec J. 176 Sedlacek Z. 060 Valach P. 193 Semenov A.Yu. 127,128,129 Valuev A.D. 170,171 130,151,187 VarDevender J .P. 219 Senatskij J.V. 147 Vasella M. 050 Sergeev A.M. 071,072 Vasin B.L. 170,171 Sercv R.V. 162,174 Velarde G. 043 Sharkov E.Yu. 181 Vergunova G.A 086,189 Sherman V.E. 096,183,184 Vinogradov A.'V. 083 Shikanov A.S. 056 Viririont J. 051,090,137 Shimanovsky D.M. 144 Volyak T.E. 127,128,151 Shimotori Y. 220 Vondrasek J. 081,106 .Shiwai B. 150 Vovchenko V.I 127,128 Shlov-sky E.I. 169 129,130,151 Shlyaptsev V.N 083 Vrtova M. 194,195,201

- 232 - Vukovic S. 061 Vygovsky O.E. 096,183,184 Waltham J. 172 Weber R. 141 Wilczynski A. 106 Will: 0. 047,066,124 136,204,205 Witkowski S. 037,207,215 Wolowski J. 106,110,132 133 Wooding E. 149 Woryna E. 085,182 Yamanaka C. 058,210 Yamaneka M. 210 Yamanake T. 210 Yanovsky V.P. 174 Yatsui K. 220 Young Y. 160 Zaitsev S.G. 126 Zakharenkov Yu.A. 182 Zammit U. 212 Zaporogets Y.B. 199 Zittel W. 091 Zmitrenko U.V. 097,098 184,188 Zubkov V.M. 171

- 233 - 18th ECLIM

EUROPEAN CONFERENCE ON LASER INTERACTION

WITH MATTER

ADDITIONAL PAPERS

Abstracts as received by March 15, 1987

- 235 - ECLIM18: ADDITIONAL PAPERS

WEDNESDAY MAY 6

P-2 POSTERS 2 11.OO - 12.30 Secretary: M. Vrbova Fac. Nucl. Sci., Tech. Univ. of Prague

Miscellaneous

P-2-33 Suprathermal Distribution Function of Electrons Interacting with Nonlinear Langmuir Waves D. GALMICHE, J.P. NICOLLE Centre d Etudes de Limeil, Villeneuve-St-Georges D. PESME Centre de Phys. Th6or. Ecole Polytechnique, Palaiseau 239 P-2-34 On the Role of Modulation Instability in a Laser Accelerator Ya.L. BOGOMOLOV, A.G. LITVAK, A.M. FEIGIN Inst. Applied Physics, Acad. Sci. USSR 240 P-2-35 Non-Uniform Irradiation with Inverse Bremsstrahlung Absorption in Spherical Laser Targets S.G. TAGARE University of Hyderabad F. IBANEZ, J.A. NICOLAS, J. SANZ ETS Ingenieros Aeronaticos, Univ. Polltec. de Madrid 241 P-2-36 Instabilities and Symmetry Effects in Laser-Plasma Interaction P.M. VELARDE, J.M. ARAGONES, L. DIAZ, J.J. HONRUBIA DENIM 242 P-2-37 Atomic Physics and Radiation Transport Simulation in Laser Fusion E. MINGUEZ, J.A, GAGO, M.L. GAMEZ, J.L. OCANA, J.M. PERLADO, J.F. SERRANO DENIM 243

- 237 - WEDNESDAY MAY 6 P-2-38 Explicit Dependence on Temperature and Density of the Nonequilibrium Populations in a Recombining Plasma I. SCHNEIDER, V. STANCALIE, I. PATEOPOL, D. APOSTOL, I.N. MIHAILESCU Central Institute of Physics, Bucharest 244 P-2-39 Some Features in Stark Broadening of Spectral Lines of Hydrogen-Like Ions in Dense Plasmas B.V. LJUBLIN, V.Yu. YASEVICH Efremov Institute, Leningrad D.G. YAKOVLEV Physical-Technical Institute, Acad. Sci. USSR 245 P-2-4O Diagnosis of Laser Produced Plasmas Using Fusion Reaction Products P.M. EVANS, A.P. FEWS Bristol University E. FABRE Ecole Polytechnique, Palaiseau W.T. TONER RAL 246 P-2-41 Third Harmonic Conversion in High Power Glass Laser System GEKKO XII for Fusion Experiment M. NAKATSUKA, T. SASAKI, Y. KATO, T. JITSUNO, K. YOSHIDA, Y. IZAWA, T. YAMANAKA, M. YAMANAKA, S. NAKAI, C. YAMANAKA ILE, Osaka University 247

- 238 - ECLIM18: P-2-33

SUPRATHERMAL DISTRIBUTION FUNCTION OF ELECTRONS INTERACTING WITH NONLINEAR LANGMUIR WAVES

D.Galmiche,J.P .Nicolle,D.Pesme*

Commissariat a l'Enargie Atonique Centre d'Etudes de Limeil/Valenton, BP 27 94190 Villeneuve Sl Georges FRANCE

In laser-plasma interaction, the Langmuir waves produced by resonant absorption or parametric instabilities are typically found to behave nonlinearly under the form of soliton-like wave packets. The production of suprathermal particles is examined by considering the interaction of test electrons with localized wave packets. The different velocity regions corresponding to quasilinear-type diffusion or trapping are determined analytically. Approximate expressions for the energy transfer probability are given for the different domains and the comparison with numerical results is made.

'Permanent address: Centre de Physique Theorique, Ecole Polyteohnique, 91128 Palaiseau Cedex FRAHCE

- 239 - ECLIM18: P-2-34

ON THE ROLE OP MODULATION INSTABILITY IN A LASER ACCELERATOR Ya.L.Bogomolov, A.G.Litvak, A.M.Peigin Institute of Applied Physics, USSR Academy of Sciences, 46 Uljanov Street, 603600 Gorky, USSR

One of the actively discussed and experimentally tested methods to produce a fast Langmuir wave (PLW) in a laser accelerator where PLW is excited under the effect of two collinear laser generation beams with close frequencies {ty,Ct)z»6)i -<*)A ) is considered. In the framework of a one-dimensional model when plasma nonlinearity in sufficiently strong fields is linked with the dependence of electron masses on the velocity of their oscillations in the wave field, modulation instability is shown to result in PLW breaking / during the time £e*3O/tJ»ct* * .Here &0 = ty-&), ±a the

PLW frequency, *>{•=• flS&Ttf p is proportional to the density of the laser generation flux ^ , is the charge and mass of rest of electrons,respectively, and C is the velocity of light. The comparison of the value of "t^ with the characteristic acceleration time enables us to assert that modulation instability for the rather intense laser generation is to break PLW prior to the acceleration of electrons resonant to PLW. The corresponding estimation for an isotopic case ( laser beat wave accelerator ) has the form 2 & and for a surfatron

Here 9 is the density of the generation flux ( in Wfcm* ), A is the wavelength ( in yum ). T- COo-laser experiments ( X«40f*m. fO0 a: O.f&i ) densities of the generation flux which are "boundary*1 from the point of view of the modulation instability effect are rather small; " " " ** "

- 240 - CCLIM18: P-2-35

NON-UNIFORM IRRADIATION WITH INVERSE BREMSSTRAHLUNG AB- SORPTION IN SPUE RICA I. LASER TARGETS

S.G. Tagare*, F. ibanez, J.A. Nicolas and J. S a n z

E.T.S.I.Aeronauticos, Universidad Politecnica 28040-Madrid, Spain

Inverse brernsstranlung absorption in the spherical, quasistead.y corona of a laser target is important for lov; intensities and short wavelengths pulses (1-2). At very low powers a thin deflagration layer appears next to the pellet surface, whose structure is well known (1) Here we assume that laser irradiation is almost spherical, justifying a linear analysis in terms of spherical harmonics. Underdense light refraction and field magnetic generation are negligible due to the low densities in the corona. It is important to take special care on the location of the critical surface. Complete results for ablation pressure, mass flow rate, and critical surface location are given in terms of Legendre index.

References 1. Nicolas J.A. and Sanirartin J.R., Plasma Physics and Controlled Fusion, 27, 279 (1985). 2. Mor 0., Physics Fluids 25, 1051 (1982).

Permanent adress •School of Mathematics, University of Hyderabad, Hyderabad 500134, INDIA.

- 241 - ECLIM18: P-2-56

INSTABILITIES AND SYMMETRY EFFECTS IN LASER-PLASMA

INTERACTION

P.M. Velarde, J.M. Aragones, L Diaz, J. J. Honrubia.

Instituto de Fusion Nuclear (DENIM). P^ Castellana 80,28046 Madrid, Spain

Several instabilities are studied in some extent performing two dimensional simulations. For mixing of two materials we have developed a 2D-hydro Particle-in- Cell (PIC) code (ARWEN). This effect can be more important than the Rayleigh- Taylor instability in some high-gain targets. Strong numerical control is needed in order to limit the numerical diffusion for reliable results. A summary of these properties is presented.

Actually Raman Scattering (SRS) remains as a problem in laser fusion. We have continued with the simulations with WAVE code in 2D. By now, results are agree qualitatively with the reported ones, but some points have to be further clarified.

We have implemented the ANTHEM code(2) (implicit PIC and MHD) for conduction problems with the produccion and amplification of B-fields (as Nernst advection). We are continuing the previous simulations about the Nernst advection with inertia, higher frecuency lasers and differents atomic numbers.

REFERENCES

1.-D. Forslund, "Fundamentals of plasma simulation" LA-UR-85-413 (1985) 2.- R. J. Mason "An Electromagnetic Field Algorithm For 2-D Implicit Plasma Simulation" LA-UR-1391 (1986)

- 242 - LCLIM18: P-<•::-••; '/

ATOMIC PHYSICS &m f?ADJATJON TRANSPORT SIMULATION SN LASER

E. Minguez. i A. 6ago; *Vf.:.. <5am&?:, i.L. Ocana, i.M. Perledo, J. F. Serrano

Institute de Fusion W^'lfc^ • :'O£^!M). Ps Cateflsns SO, 28046 Madrid, Spain

The main features of the f.op.ioW; plasmas produced in solid targets due to laser irradiatiorv art their high den>!ty; the partial ienization and the iarge optical thickness. In this situation, the calculaticr: of atomic data like EOS, opacities and conductivities for the hydrodinarrx process and the radiation transport is quite difficult, because of the physical processes that have to be considered.

The goal of this paper should be to explain me progress at DENIM in the atomic physics rnodeis development and also in the muitigroup radiation model coupled to the hydrodynamic NORMA code.

First, the present state of the DHNIM-A i iih^ry for atomic data processing and do ,-; recently evaluated for several msteriate li«e eh;minium europium, gold, argon and xenon are compared with those results given in the literature.

Numerical models in atomic physics to generate the former data and a numerical model to determine the equilibrium distribution of ionization states by solving the rate equations are also presented.

Finally, using the new algorithm developed at DENIM to solve the multigroup radiation diffusion equations coupied with the hydrodynamic equations, the results obtained for several cases are presented and discussed.

- 243 - ECLIivli8: P-2-33

EXPLICIT DEPENDENCE ON TEMPERATURE AND DENSITY OF THE NONEQUILIBRIUM POPULATIONS IN A RECOMBINING PLASMA

I. Schneider, V. Stancalie, I. Pateopol, D. Apostol, I.N. Mihailescu

Central Institute of Physics, Bucharest, Romania

The collisional-radiative model for a recombining plasma (1 '2 ) proved to be very successful in evaluating the populations of the different nonequilibrium quasistationary levels. Our intention is to obtain a more explicit dependence of the "relative" populations on electronics density n and electronics temperature T. Calculation procedure, based on matrix algebra, is described and an example for a "hydrogenic" plasma with z = 1 is given,

1. D.R. Bates, A.E. Kingston, R.W.P. McWhirter: Proc. R. Soc. A 267 (1962), 297 2. H.W. Drawin, F. Emard: Euratom Rept. EUR-CEA-FC (1970), 534

- 244 - ECLIM18: P-2-39

SOMZ FEATURE; lu STARK BROADENING OP SPECTRAL LINES <}? }:"'.!#OGJDN-LIKii IONS IN DENSii PLASMAS B» V*Ljuolin, D.G.Yakovlev*, V.Yu.Yasevich D«V.j!;fre::iov Scientific Research Institute of iilectrophysi.c: s -2,... The relative intensities of the satellites may be used to determine the strength and polarization of the laser field and, hence, the power of the laser radiation in a plasma. The Stark splitting of profiles by an intense field of GOp laser and also by the first and second harmonics of Nd laser are calculated. In addition, the hydrogen-like L^ and L^ profiles are considered for the case of resonant interaction between quasi- -static and harmonic electric fields in dense plasmas.

245 _ ECL1M18:

DIAGNOSIS OF LASER PRODUCED PLASMAS USING FUSION REACTION PRODUCTS

P.M. Evans, A.P, Fews

Bristol University, Bristol, UK

E. Fabre

Ecole Polytechnique, France

W. T. Toner

Rutherford Appleton Laboratory, UK

Experiments have been performed at the Central Laser Facility, Rutherford Laboratory and at Ecole Polytechnique, Palaiseau, in which laser produced plasmas have been diagnosed by measurements of the charged thermonuclear reaction products. Three types of experiment have been performed. 1. Measurement of the degree of compression and uniformity of laser driven implosions have been made. This has been achieved be measurement of the energy loss of individual thermonuclear alpha particles and protons escaping from the target. 2. Thermonuclear alpha particles have been used to determine the growth of Rayleigh Taylor instability in a separate laser driven planar foil. The resulting alpha particle range loss distributions provide a direct measurement of the foil thickness distribution. The technique is useful for measuring small scale lenght instabilities. 3. This thermonuclear particle backlighting technique has also been used in the measurement of plasma stopping power for different materials. The ratio of plasma stopping power to the of cold material can thus be found. The solid state nuclear track detector CR39 has been used as a diagnostic for all these experiments. A sophisticated image analysis system has been developed to enhance ana improve data recovery.

- 246 - ECLIM18: P-2-41

THIRD HARMONIC CONVERSION OF HIGH POWER GLASS LASER SYSTEM GEKKO XII FOR FUSION EXPERIMENT M. Nakatsuka, T. Sasaki, Y. Kato, T. Jitsuno, K. Yoshida, Y. Izawa, T. Yamanaka, M. Yamanaka, S. Nakai and C. Yamanaka Institute of Laser Engineering, Osaka University 2-6 Yamada-oka, Suita, Osaka 565, Japan

Shorter wavelength of the implsion driver is well known to have good properties on an absorption efficiency,, supressinn of hi oh energy electron generation and Xray conversion efficiency. We nave started the installation of the 3OJ frequency conversion optics and irradiation system on the second target chamber room of the GEKKO XII glass laser facility, and completed four beam system in the end of 1986. Frequency conversion of 35cm large aperture laser beam is attained by the four segmented KDP arrayed crystals set in one cell as 2u) conversion and 3OJ wave mixing generation. We adopted polarization-mismatch scheme for frequency tripling in which 12mm thick type-II KDP crystals were used. The fabrication method of a quarter-circuler plate of KDP crystal was established with sufficient accuracy of its shape, thickness, surface paralellism and flatness, roughness and phase matching angle using the diamond turning machine. Eight fan-type KDP crystal plates were set in a single frame with quartz windows. The gap spacing between KDPs and windows was kept 100um by the pricisely machined metal tips.

High power shot test has resulted in the total conversion efficiency up to 65% at an incident intensity of 1.5^3.0GW/cm2. The output pattern of each 4 segment beams shows very good uniformity in 3d) conversion. The experimental results of the focusing characteristics, the simulation analysis of the irradiation properties on the spherical target and the improvement of the irradiation uniformity by a random phase mask will be discussed.

- 247 - INDEX TO AUTHORS: ADDENDUM

Apostol D, 244 Toner W.T. 246 Aragones 3.M. 043, 242 Turek 3« 180 Bahr R. 052 Valnicek Bo 180 Bogomolov Ya.L. 240 Velarde P.M. 043, 242 Calmiche D. 239 Verdon C .P. 052 Diaz Lo 242 Yakovlev D.G. 245 Evans P.M. 246 Yamanaka c. 247 Fabre E. 246 Yamanaka M. 247 Feigin A.M. 240 Yamanaka T. 247 Fews A.P. 246 Yasevich V.Yu. 245 Gago 3.AO 243 Yoshida K. 247 Gamez M.L. 243 Gardner 3OHO 216 Giuletti A. 173 Giuletti D. 173 Honrubia 3.D. 043, 242 Hudec P. 180 Ibanez F. 241 Izawa Y# 247 Jaaminagi P.A. 052 3itsuno T. 247 Kato Y. 247 Kessler T.3. 052 Litvak A.G. 240 Ljublin B.V. 245 Lucchesi M. 173 Marshall F.3. 052 Martinez-Val 3.M, 043 Mihailescu I.N. 244 Minguez E, 043, 242 Nakai S. 247 Nakatsuka M. 247 Nicolas 3.A. 241 Nicolle 3.P. 239 Nocera L. 173 Ocana 3.L. 043, 243 Pateopol I. 244 Perlado 3.M. 043, 243 Pesme D. 239 Pina L. 151 Renner 0. 198 Richardson M.C. 052 Sanz 3. 241 Sasaki T. 247 Schneider I. 244 Seka W. 052 Serrano 3.F. 243 Skupsky S. 052 Soures 3.M. 052 Stancalie V. 244 Tagare S.G. 241

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