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Capsule design for the National Ignition Facility

Published online by Cambridge University Press:  01 April 1999

T.R. DITTRICH
Affiliation:
Lawrence Livermore National Laboratory, Livermore, CA
S.W. HAAN
Affiliation:
Lawrence Livermore National Laboratory, Livermore, CA
M.M. MARINAK
Affiliation:
Lawrence Livermore National Laboratory, Livermore, CA
D.E. HINKEL
Affiliation:
Lawrence Livermore National Laboratory, Livermore, CA
S.M. POLLAINE
Affiliation:
Lawrence Livermore National Laboratory, Livermore, CA
R. McEACHERN
Affiliation:
Lawrence Livermore National Laboratory, Livermore, CA
R.C. COOK
Affiliation:
Lawrence Livermore National Laboratory, Livermore, CA
C.C. ROBERTS
Affiliation:
Lawrence Livermore National Laboratory, Livermore, CA
D.C. WILSON
Affiliation:
Los Alamos National Laboratory, Albuquerque, NM
P.A. BRADLEY
Affiliation:
Los Alamos National Laboratory, Albuquerque, NM
W.S. VARNUM
Affiliation:
Los Alamos National Laboratory, Albuquerque, NM

Abstract

Several choices exist in the design and production of capsules intended to ignite and propagate fusion burn of the deuterium–tritium (D–T) fuel when imploded by indirect drive at the National Ignition Facility (NIF). These choices include ablator material, ablator dopant concentration and distribution, capsule dimensions, and X-ray drive profile (shock timings and strengths). The choice of ablator material must also include fabrication and material characteristics, such as attainable surface finishes, permeability, strength, transparency to radio frequency and infrared radiation, thermal conductivity, and material homogeneity. Understanding the advantages and/or limitations of these choices is an ongoing effort for LLNL and LANL designers. At this time, simulations in one-, two-, and three-dimensions show that capsules with either a copper-doped beryllium or a polyimide (C22H10N2O4) ablator material have both the least sensitivity to initial surface roughnesses and favorable fabrication qualities. Simulations also indicate the existence of capsule designs based on these ablator materials which ignite and burn when imploded by less than nominal laser performance (900-kJ energy, 250-TW power, producing 250-eV peak radiation temperature). We will describe and compare these reduced-scale capsules, in addition to several designs which use the expected 300-eV peak X-ray drive obtained from operating the NIF laser at 1.3 MJ and 500 TW.

Type
Research Article
Copyright
© 1999 Cambridge University Press

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