Inertial Confinement Fusion [annual rpt 1988-89]

658 Pages·1993·42.087 MB·English

UCRL- LA-/dSg_d- _2/_'
Distribution Category UC-712
MS Date September 1993
1988/89
ICF
Program
Annual
Report
Lawrence Livermore
MASIER National Laboratory
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Preface
This report documents the major activities and accomplishments of the Inertial Confinement Fusion
(ICF) Program, apart of the Laser Programs at Lawrence Livermore National Laboratory (LLNL), during
the 1988-89 calendar years. Prior to 1988, ICF documentation was included in the Laser Programs
Annual Report, which was last published in 1987. Beginning in 1991, anew reporting structure was
established: the ICFQuarterly Reports and the ICF Annual Report. The ICFQuarterly and Annual
Reports began documenting activities by fiscal year rather than calendar year, for ease in tracking
progress against project plans and budgets (which are based on the fiscal calendar). Because the fiscal
year 1991 Annual Report was a new publication, it covered both calendar year 1990 and fiscal year
1991--the period from January 1,1990 to September 30, 1991.
This 1988-89 ICF Annual Report is organized into seven sections, beginning with an executive
summary overview and followed by six additional sections that describe accomplishments within the
major research and development areas of ICF: Target Physics, Nova Experiments, Nova Laser Science
and Technology, Target Science and Technology, Advanced Drivers, and ICF Applications.
D. L. Correll
Acknowledgments
As in previous years, scientists, engineers, technicians and other staff members continued to provide
incredible effort in support of the LLNL ICF program. Not surprisingly, their aid and cooperation in
completing this 1988-89 Annual Report have been invaluable. We are especially grateful to those who
wrote and contributed to the articles; their efforts are the backbone of this document.
Members of the Laboratory's Technical Information Department shaped the raw material into a final
product. Editors Jason Carpenter, Pete Murphy, Joy Perez and Leslie Wilder, with proofreading
assistance from AI Miguel, tackled the task of polishing the articles, fitting them together, and pushing
the whole package to completion. For the excellent artwork we thank the production staff: Chuck
Chapman, Galen Hazelhofer, C. Sue Lawrence, Kim M. Lanto, Daniel Moore, and Don Ryder. Ron Natali
saw the document through the printing process.
Many of ICF's secretarial staff contributed, as well. Those who played a principal role were Gloria
Baker, Carol Molkenbuhr, and Nanci Strange. Special thanks go to Pamela D. Dickinson, who not only
added to the artwork but also provided the layout and managed the data throughout the project's history.
We sincerely thank all those people above, as well as the many unnamed, for making possible the
1988-89 ICF Program Annual Report.
D. L.Correll
_ova Experiments
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Overview
........ i iii i
1. ICF Program Overview
The continuing mission of the Inertial target preheat, and hydrodynamic stability
Confinement Fusion (ICF) program is to develop required for ignition and gain. The LLNL Nova
the science and technology base necessary to laser facility is the primary U.S. facility
determine the technical feasibility of achieving devoted to the study of the indirect (or
significant fusion energy yields in the hohlraum) drive approach to inertial fusion. In
laboratory, to identify applications utilizing this concept, energy from a laboratory driver is
that capability, and to develop the most converted by the hohlraum walls to radiation
promising of these applications. This mission that is used to implode and heat the fusion fuel
has required developments in the fields of high inside of an inertial fusion capsule that is
energy density physics and high peak-power/ centered within the hohlraum. We continue to
energy laser science and technology, and use Nova to study inertial confinement fusion,
supporting technologies, laser-plasma interaction physics, weapons
Our near-term goal is to apply ICF physics, and laser science.
technology and facilities to provide a better The major research and development areas of
understanding of nuclear weapons physics issues, our ICF program fall in the following categories:
A longer-term goal is to explore the feasibility Target Physics, Nova Experiments, Nova Laser
of ICFas a clean and inexhaustible source for Science and Technology, Target Science and
commercial electric power production. The Technology, Advanced Drivers, ICF
potential defense applications of ICF physics Applications, and Halite/Centurion.
and technology include studying basic atomic Our Target Physics advances included
physics and hydrodynamics, extending significant code development: the new DIMPLE
capabilities to simulate the effects of nuclear code calculates the evolution of small-amplitude
weapons on hardware that must function in a perturbations from spherically symmetric flow;
nuclear environment, developing instrumentation the LASNEX code helped us investigate
and techniques that can be applied to full-scale holographic interferograms; and a new package
nuclear tests, and exploring the basic principles in LASNEX can calculate electron heat
of advanced weapons concepts, conduction. In atomic physics, we developed a
The primary scientific requirement for new "atom-in-jellium" condensed-matter model.
realizing the full defense and energy X-Division's laboratory x-ray laser (LXRL)
applications of ICF is the achievement of net research included new table-top LXRL design
fusion gain (fusion energy produced/driver approaches, study of large-laser-pumped LXRL
energy required). The ICF Program has made systematics, calculation of LXRL-source
substantial progress in ICF target physics and coherence for holography, and new escape-
laser science and technology. In each of these probability methods for planar and cylindrical
areas, progress required the development of geometries. In addition, we investigated heavy-
experimental techniques and computational ion particle accelerators as drivers for inertial
modeling. Our recent experiments and modeling fusion power production. We also made advances
are focused on the physics necessary to validate in the theory and design of targets, in target
the basic concept of fusion ignition and gain in fabrication and materials science, in laser and
the laboratory, optics research, and in diagnostics. With the
The Nova laser is the latest in a series of benefit of experiments at higher drive energies,
ever more powerful laser facilities at LLNL. and using the sophisticated temporal pulse
Nova's principal objective is to demonstrate that shaping capability of Nova and the advances in
laser-driven hohlraums (hollow chambers that diagnostic capability, future work will refine
trap electromagnetic radiation) meet the target designs.
conditions of beam/target coupling efficiency, Our Nova Experiments have covered much
beam irradiation symmetry, beam pulse shaping, ground. We have learned that a correlation can
1-1
Overview
i
exist between second-harmonic emission and high-density/temperature materials,
density perturbations from an underdense high-acceleration instabilities, laser driver
plasma; that plasma densities and temperatures characterization, and diagnostic development.
at late time depend on initial target geometry; To achieve this, the program's work includes
and that harmonic light images can be fabrication and production, development,
significantly refracted. We incorporated characterization, and material research.
SIMPLE, a one-dimensional, three-fluid, local The Advanced Drivers Program has two
thermodynamic equilibrium, hydrodynamics objectives: upgrade Nora's performance
code for small computers, into our computational capabilities, and develop future drivers for the
studies. Other work in hydrodynamics promises 1CF Program. The Precision Nova Project aims to
improved computational models. And in 1989, improve target irradiation through better energy
the LLNL laboratory x-ray laser team produced and power balance, pointing accuracy, and
amplified spontaneous emission (i.e. lasing) at diagnostics. The beam "smoothing" project looks
4.48 nm in nickel-like tantalum. This is a to develop large aperture phase plates for
significant step toward the achievement of an spatial incoherence and broadband,
x-ray laser source for holographic microscopy of multifrequency laser oscillators for temporal
living biological cells. In diagnostics, we incoherence. In pursuit of the second objective, we
developed a multichannel W61ter x-ray focused on two laser concepts, "Loki" and
microscope for time and space resolved high "Athena." Although we decided to discontinue
resolution x-ray images of laser fusion work on Loki, we nevertheless invented in its
experiments; a thick aperture design for neutron support a new laser material, chromium doped
penumbral imaging that achieves at least 10-_m lithium calcium aluminum fluoride (LiCaF).
resolution over a 150-1J.m field of view without Most of our work went toward Athena, with an
significant first-order distortion; and the objective to meet all technical requirements for
MOSFET/NLTL avalanche diode pulser, an the Laboratory Microfusion Facility. Our
alternative picosecond high voltage pulser for activities, aimed at making Athena less
new gated x-ray camera structures and ultra-fast expensive than previous Nd:glass laser systems,
transient digitizer topologies, included improvements in system efficiency and
Supporting the Nova experiments are the increases in energy storage density and laser-
Nova Operations and Laser Science groups, induced damage thresholds. In addition, the
whose accomplishments in 1988 and 1989 were Advanced Drivers Program completed other
many. Installation of platinum-free glass and research in optical materials and laser design
fused silica lenses brought Nova to its full and performance.
operational potential. We have evaluated Investigating ICF applications, we made
system damage, crystal conversion efficiency, substantial progress in the development of
and beam uniformity, making changes tobeam concepts and technologies for the next higher
apodizers, amplifier configurations, beam energy laser facility for ICF. The ICF
fill-factors and pinhole sizes. We began or Applications group revised both the HYLIFE-I
continued upgrades and maintenance in streak and CASCADE power plant designs, including
cameras, flashlamps and oscillator capability, the development of a vacuum system for both
Nova continues to operate 12 hours a day, with concepts.
Monday set aside as a maintenance day. During In a program called Halite/Centurion, a portion
1989, we fired 584 high-power shots to provide ofenergy from a nuclear device in underground
the drive source for 675 experiments. The explosions at the Nevada Test Site was used to
energies provided by the laser (at a wavelength implode inertial fusion capsules. Halite is the
of 1.06 Bin) ranged from <1.0 kJto >120 kJ. Pulse name of the program under the leadership of
durations varied from 10ps to several LLNL; a similar program named Centurion was
nanoseconds. Temporal pulse shapes included guided by Los Alamos National Laboratory.
square, Gaussian, and specially shaped pulses Because the ability to fully study and
designed to improve target performance, understand the performance of ICF capsules in
Our Target Science and Technology Program the laboratory has been limited by the energy
provides targets for fusion experiments, x-ray and power that can be provided with presently
lasers, and laser matter-plasma interaction available lasers, _he Halite/Centurion program
studies, as well as experimental activities in extended the renge of inertial fusion research. As
1-2
I
Overview
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described in a Department of Energy (DOE)
Inertial Fusion fact sheet, "the combination of
data obtained from laboratory experiments and
the Halite/Centurion program has enabled the
DOE's Inertial Fusion Program to progress at a
faster rate than anticipated. Many issues
related to its scientific feasibility have been
firmly established. As a result, DOE has begun
preliminary planning to determine whether a
new facility is feasible and affordable. The new
facility under study, called the Laboratory
Microfusion Facility (LMF), would be capable of
achieving fusion routinely and generating one
billion joules (1000 MJ) of energy, the energy
equivalent to one quarter ton of TNT. The DOE
Inertial Fusion Program Office is currently
proceeding with studies aimed at defining the
cost basis and performance of the LMF."
While Nova has insufficient energy to
achieve ignition and gain, we believe that
detailed and quantitative experiments in future
Nova hohlraum and capsule physics, coupled
with the experimental results achieved with
Halite/Centurion, will provide a sufficient data
base to confidently predict ignition and gain
performance within the laboratory.
1-3
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Target Physics
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Contents
2. Target Physics ................................................................................................................................................... 2-1
2.1. Introduction ........................................................................................................................................... 2-1
2.2. Implosion and Ignition Physics ........................................................................................................... 2-1
2.2.1. Introduction ................................................................................................................................ 2-1
2.2.2. LASNEX Simulations of the Classical and Laser-Driven
Rayleigh-Taylor Instability ................................................................................................................. 2-1
2.2.3. Stability and Mix in Spherical Geometry ............................................................................... 2-1
2.2.4. Rayleigh-Taylor and Richtm_,er-Meshkov Instabilities and
Mixing in Stratified Spherical Shells ................................................................................................. 2-1
2.2.5. Raylei_h-Taylor and Richtmyer-Meshkov Instabilities in
Multilayer fluids with Surface Tension ........................................................................................... 2-2
2.3. Code Development and Atomic Physics ........................................................................................... 2-2
2.3.1 A Linear Perturbation Code, DIMPLE ..................................................................................... 2-2
2.3.2. A Fokker-Planck Treatment of Suprathermal Electron
Heat Conduction .................................................................................................................................. 2-5
2.3.3. Cylindrical Escape Probabilities for X-Ray Laser
Modeling ............................................................................................. .................................................. 2-6
2.3.4. Holographic Interferograms from LASNEX Simulations .................................................... 2-6
2.3.5. Test Problems for Radiative Transfer Codes ......................................................................... 2-7
2.3.6. Atomic Vibrations in a Self-Consistent Field Atom-in-
Jellium Model of Condensed Matter (Fig. 2-7) ................................................................................ 2-7
2.3.7. Modeling Doppler Broadening in Raman Propagation ....................................................... 2-8
2.3.8. Efficient, High-Order Solution Technique for the Liouville
Equation ................................................................................................................................................. 2-8
2.3.9. Liouville Equation in the Presence of Non-Colinear Light
Beams ..................................................................................................................................................... 2-8
2.3.10. Generation of Harmonic Radiation During Electron
Scattering from a Piecewise Constant Potential in an Intense
Electromagnetic Field .......................................................................................................................... 2-8
2.3.11. Electron Scattering Assisted by an Intense
Electromagnetic Field--Exact Solution of a Simplified Model ..................................................... 2-8
2.4. Progress in Plasma Physics .................................................................................................................. 2-9
2.4.1. Overview of Plasma Physics Research ................................................................................... 2-9
2.5. X-Ray Laser Design .............................................................................................................................. 2-12
2.5.1. Introduction ................................................................................................................................ 2-12
2.5.2. Plasma Physics Issues in Laborato_ X-Ray Lasers .............................................................. 2-12
2.5.3. Sensitivi_ of Recombination X-Ray Laser Gain
Predictions to Atomic Physics ............................................................................................................ 2-12
2.5.4 Studies of High-Z Exploding Foils Irradiated by Combined
Long (2 ns) and Short (10 ps) Pulses of 10_Light ............................................................................. 2-13
2.5.5. Scaling Laws for Femtosecond Laser-Plasma Interactions .................................................. 2-13
2.5.6. Study of Soft X-Ray Amplification in aLaser-Produced
Strontium Plasma ................................................................................................................................. 2-13
2.5.7. Collisional Excitation X-Ray Laser Experiments in Plasmas
Produced by 0.53-mm and 0.35-mm Laser Light ............................................................................ 2-13
2.5.8. Hydrogen-like Magnesium X-Ray Laser Design ................................................................... 2-14
2.5.9. New Calculations for Ni-Like Soft X-Ray Lasers
Optimization for W(43.1._) ............................................................................................................... 2-14
2.5.10. Modal Analysis of X-Ray Laser Coherence .......................................................................... 2-15
2.5.11. The Development of Coherent X-Ray Lasers for X-Ray
Holography ........................................................................................................................................... 2-15
2.5.12. Apl_lication of Escape Probability to Line Transfer in
Laser-Proauced Plasmas ..................................................................................................................... 2-16
2.5.13. The Calculation of Line Transfer in Expanding Media ...................................................... 2-16
2-i