—— .. h Affiitive AcUoet/Equal@p@lSlity Erl@Oyer The four most recent reports in this series, unclassified, are LA-7587-PR, LA-7755-PR, LA-8 114-PR, and LA-851 I-PR. This work was supported by the US Department of Energy, OffIce of InertiaI Fusion. Compiled by Frederick Skoberne Edited by Helen M. Sinoradzki and Jody Heiken Photocomposition by the Group IS-6 Composing Section DISCLAIMER Thisreport waspreparedasanaccount of work sponsoredby an agencyof the United States Government. Neitherthe United States Governmentnor any agencythereof, nor any of their employees,makesany warranty,expressor implied,or assumesany legalliabilityor responsibilityfor the accuracy,completeness, or usefulsmsaof any information,apparatua,product, or processdisclosed,or representsthat its usewould not infringeprivatelyownedrights. Referenceshereinto any specMccommercialproduct, process,or sertice by trade name, trademark,manufacturer,or otherwise,doesnot nemaarily constitute or implyits endorsement,recormnen&tion,or favoringby the UnitedStatesGovernmentor any agencythereof. The viewsarrdopiniom of authors expressedhereindo not necessarilystate or reflectthose of the United States Coveromentor any agencythereof. LA-9086-PR Progress Report UC-21 Issued: May 1982 Inertial Fusion Program January—December 1980 9 i : The Inertial Fusion Program Staff I Los Alamos National Laboratory b~~l~~~s ,...,..............87... CONTENTS ,ACRONYMS . vii ABSTRACT . 1 SUMMARY . 2 Introduction ..,...,.. ...2 OperatingCOz Laser Systems. 2 Antares—HighEnergyGasLaser Facility . 2 AdvancedLaserTechnology. , . 3 Target Experiments .,.... ...4 Diagnostics Development . .’ . 4 LaserFusionTheoryandTarget Design ~ . 5 LaserFusionTargetFabrication . ...5 Heavy-IonDriverDevelopment . 6 Systems andApplications Studies ofInertialFusion . 7 LOPERATINGCOZLASERSYSTEMS . 8 Helios Laser System . ...8 GeminiLaserSystem . 11 II. ANTARES—HIGHENERGYGAS LASER FACILITY . 13 Introduction . ...13 Optical System . 13 LargeOpticalComponents. ...17 Front-End System . ...18 PowerAmplifierSystem . .. ...19 EnergyStorage System . ...25 AntaresTargetSystem . ...26 Control System . ...33 III. ADVANCED LASERTECHNOLOGY . 38 StudiesofAntares andHeliosLaser Systems . 38 StudiesinNonlinearMedia . 47 Advanced C02LaserDevelopment . 60 Advanced Concepts . 83 GigawattTestFacility . 93 References . ...94 IV. TARGETEXPERIMENTS. 99 Introduction, . ...99 Integrated Absorption Experiments on COZ Laser-Generated Plasmas . 99 Lateral Transport of Energy from aLaser-Produced Plasma . 102 Visible Harmonic Generation in C02Laser Fusion Experiments . 103 High-Energy X-Ray Measurements at Helios . 105 MULTIFLEX Fast X-Ray Detection System . 106 Effect of Hydrogen in COZ Laser-Induced Plasmas . 106 Backscatter and Harmonic Generation Measurements in Helios . 114 References . ...115 iv ? V. DIAGNOSTICS DEVELOPMENT . ., .,,,117 Introduction ..,,,,,,., ... .,, . ..om. .om . ...117 X-Ray Diagnostics . ., . .. $000117 Pulsed Calibration of a Proximity-Focused X-Ray Streak Camera . , , , . , , . 119 Detector Response Functions for MULTIPLEX . , . , . , . , . , , , 122 A “Thin Lens” Electron Magnetic Spectrometer and an Electron Ray-Tracing P Code for Cylindrically Symmetric Fields . , . , . , . 126 Slit-Viewing Homogeneous Sphere: Least Squares Fitting of Analytical Expressions to Image Data....,,.,,,,. , ...,..129 Reconstruction of X-Ray Emission Profiles of Imploded Targets from Slit Photographs . 130 Optical Plasma Diagnostics . , ...,...132 Data Processing . .,, , .,, ,,, ,. .,,,... ...00.139 References . ...139 VI. LASER FUSION THEORY AND TARGET DESIGN . , . 141 Target Physics . ...141 Fuel Temperature Determination for ICF Microsphere . , , , . , . 144 Supporting Physics . ., .,,,,.147 Code Development.......,,. ., . ...152 References . ..16s VII. LASER FUSION TARGET FABRICATION . , , . , . , , , , . 171 Introduction . ...171 Target Fabrication . , . ...172 Target Characterization . ...177 Laser Fusion Target Coatings . ...185 Low-Density Organic Foam and Fibrous Material Development . , , . , 198 Cryogenic Target Development . ..2o2 References . .,.,.....,206 VIII. HEAVY-ION DRIVER DEVELOPMENT . 0 . 208 Introduction . ...208 Accelerator Development..,.. , ...,...208 Beam Transport . ...211 References . , ..,,,....212 IX. SYSTEMS AND APPLICATIONS STUDIES OF INERTIAL FUSION . 215 Introduction . .,..,..,.215 ICF System Integration . .,,....215 Inertial Fusion Commercial Applications Systems Code Development . , , . 219 Reactor Studies . ,, .,......220 Heat Transfer from Graphite Liners to Coolants . 227 C02 Laser Capital Costs and Efficiencies for ICF Commercial Applications . 229 References . ...236 X. RESOURCES, FACILITIES, AND OPERATIONAL SAFETY . , . 237 Manpower Distribution . ...237 Facilities . ...237 Operational Safety . ...237 v XI. PATENTS, PUBLICATIONS, AND PRESENTATIONS . 238 patents . ...238 Publications . ...238 Presentations . ..24o ACRONYMS ASE amplified spontaneous emission BSS Beam Simultaneity System CCD charge-coupled diode CTSS Cray Time Sharing System CVD chemical vapor deposition DFP drill, till, and plug DFWM degenerate four-wave mixing DPH diamond pyramid hardness EGTF Electron-Gun Test Facility EMI electromagnetic interference FCT flux-corrected transport FFT fast Fourier transform FIF fast isothermal freezing FOM figure of merit GMB glass microballoon gOL gain-length product GWTF Gigawatt Test Facility HCC Harshaw Chemical Co. HEGLF High Energy Gas Laser Facility HIF heavy-ion fusion ICCG Incomplete Cholesky Conjugate Gradient ICF Inertial Confinement Fusion LLNL Lawrence Livermore National Laboratory LOM lowest order mode LPP low-pressure plasma LTSG laser-triggered spark gap MCNP Monte Carlo code for neutron and photon transport MCP microchannel plate MHD magnetoh ydrodynamic MI machine interface NBS National Bureau of Standards NRC National Research Council OAS Optical Assembly Shop OEL Optical Evaluation Laboratory OTB optical test bed PAM power amplifier module PDM Pittsburgh-Des Moines Steel Co. PIC particle-in-cell PVD physical vapor deposition vii RFQ radio-frequency quadruple RIO reinfection oscillator Scc subsystem-control computers S/D sorptionldiffusion SEM scanning electron micrograph SNL Sandia National Laboratories SPDT single-point diamond-turning (cd) TDR time-domain reflectometry TEA transversely excited atmospheric pressure TPA triple-pass amplifier TVS target vacuum system VPP vapor phase pyrolysis XRD x-ray diode YIG yttrium-ion-garnet ... Vlll INERTIAL FUSION PROGRAM January-December 1980 by The Inertial Fusion Program StafY ABSTRACT Our progress in developing high-energy short-pulse carbon-dioxide laser systems for fusion research is described. Because of increased efficiency and reliability, Helios, our eight-beam system, was fired 986 times, achieving on-target energies exceeding 9 kJ and pulse lengths as short as 600 ps. The Laboratory’s two-beam Gemini system was fired 511 times; 479 of these shots produced the desired energy on target without measurable prepulse or prelaser energy. The Antares effort, which was redirected from a 100-kJ, six-beam system to a 40-kJ, two-beam design to have an experimental facility available 2 years earlier than originally planned, made significant progress. This report summarizes our research and development effort in support of the Inertial Confinement Fusion program, including absorption measurements with an integrating sphere, generation of high C02-laser harmonics in the backscattered light from laser plasmas, and the effects of hydrogen target contamination on the hot-electron temperature and transport. The development of new diagnostics is outlined and measurements taken with a proximky-focused x-ray streak camera are presented. High gain in phase conjugation using germanium was demonstrated, data were obtained on retropulse isolation by plasmas generated from metal shutters, damage thresholds for copper mirrors at high fluences were characterized, and phase conjugation in the ultraviolet was demonstrated. Significant progress in the characterization of targets, new techniques in target coating, and important advances in the development of low- density, small-cell-size plastic foams that permit highly accurate machining to any desired shape are presented. The results of various fusion reactor system studies are summarized. SUMMARY (Inertial Fusion Staff) INTRODUCTION ● successful demonstration of 4-GHz data-channel recording in the control-room area; and The goal of the Inertial Fusion Program at the Los . continued development of a distributed computer- Alamos National Laboratory is to determine the require- based control and data-processing system. ments for scientific breakeven in targets driven by laser fusion. Achieving this goal will allow us to appraise the feasibility of this technique for commercial power gen- Gemini eration. This challenging scientific goal requires a broadly based program that includes the development of Gemini was used mainly in support of target experi- high-power lasers, the design and analysis of suitable ments. These experiments required 511 shots, 479 of targets, experiments to provide input for theoretical which produced the desired energy on target without modeling, the development of appropriate diagnostics, measurable prepulse or prelase energy. Noteworthy and conceptual studies for the eventual commercial use accomplishments include of inertial fusion. ● completion of 13 different target experiments. During this reporting period, the main-sequence ex- ● assembly of the new front-end screen room. periments were carried out by two.