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Proceedings Paper

Gold wall ablation and hohlraum filling measurements of vacuum and gas-filled hohlraums
Author(s): Thomas E. Tierney IV; James A. Cobble; Barbara G. DeVolder; Nelson M. Hoffman; David L. Tubbs; Paul A. Bradley; S. Robert Goldman; Glenn R. Magelssen; Dennis L. Paisley
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Paper Abstract

An understanding of the timing and dynamics of hohlraum filling by laser-induced gold wall ablation is critical to the performance of indirectly-driven fusion ignition designs for the National Ignition Facility [E. Moses and C. Wuest, Fusion Science and Technology, 43, 420 (2003)]. Hohlraum wall ablation negatively affects ignition hohlraum performance by (1) reducing laser coupling by increasing backscatter by laser plasma instabilities, e.g., stimulated Brillouin scattering, (2) altering where lasers couple by moving the critical surface away from the walls and changing the refractive index, and (3), in the case of vacuum hohlraums, ablating directly into contact with the ablation layer of the fuel capsule. We report on measurements of gold-filling of hohlraums from a series of OMEGA laser [T.R. Boehly, R.L. McCrory, C.P. Verdon et al., Fusion Engineering and Design, 44, 35 (1999)] experiments involving vacuum and gas-filled hohlraums. On-axis x-ray imaging of gold self-emission shows delayed filling for gas-filled hohlraums, as expected. In addition, we present data on the hohlraum temperature penalty incurred with the use of a 1-atmosphere methane-fill. We discuss data and simulation predictions for 1-atmosphere neopentane filled hohlraums driven with a modified laser pulse.

Paper Details

Date Published: 7 June 2006
PDF: 12 pages
Proc. SPIE 6261, High-Power Laser Ablation VI, 626106 (7 June 2006); doi: 10.1117/12.686292
Show Author Affiliations
Thomas E. Tierney IV, Los Alamos National Lab. (United States)
James A. Cobble, Los Alamos National Lab. (United States)
Barbara G. DeVolder, Los Alamos National Lab. (United States)
Nelson M. Hoffman, Los Alamos National Lab. (United States)
David L. Tubbs, Los Alamos National Lab. (United States)
Paul A. Bradley, Los Alamos National Lab. (United States)
S. Robert Goldman, Los Alamos National Lab. (United States)
Glenn R. Magelssen, Los Alamos National Lab. (United States)
Dennis L. Paisley, Los Alamos National Lab. (United States)

Published in SPIE Proceedings Vol. 6261:
High-Power Laser Ablation VI
Claude R. Phipps, Editor(s)

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