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Title: Hydrodynamic instability experiments with three-dimensional modulations at the National Ignition Facility

The first hydrodynamic instability growth measurements with three-dimensional (3D) surface-roughness modulations were performed on CH shell spherical implosions at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)]. The initial capsule outer-surface amplitudes were increased approximately four times, compared with the standard specifications, to increase the signal-to-noise ratio, helping to qualify a technique for measuring small 3D modulations. The instability growth measurements were performed using x-ray through-foil radiography based on time-resolved pinhole imaging. Averaging over 15 similar images significantly increased the signal-to-noise ratio, making possible a comparison with 3D simulations. At a convergence ratio of ~2.4, the measured modulation levels were ~3 times larger than those simulated based on the growth of the known imposed initial surface modulations. Several hypotheses are discussed, including increased instability growth due to modulations of the oxygen content in the bulk of the capsule. In conclusion, future experiments will be focused on measurements with standard 3D ‘native-roughness’ capsules as well as with deliberately imposed oxygen modulations.
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  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. General Atomics, San Diego, CA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 2095-4719; applab
Grant/Contract Number:
Accepted Manuscript
Journal Name:
High Power Laser Science and Engineering
Additional Journal Information:
Journal Volume: 3; Journal ID: ISSN 2095-4719
Cambridge University Press
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
Country of Publication:
United States
42 ENGINEERING; 70 PLASMA PHYSICS AND FUSION; hydrodynamic instabilities
OSTI Identifier: