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(IFP/05) Experimental Program to Elucidate and Control Stimulated Brillouin and Raman Backscattering in Long-Scale Plasmas

   
J. C. Fernández , J. A. Cobble , D. S. Montgomery  and M. D. Wilke 
 
Los Alamos National Laboratory, Los Alamos, NM, 87544 USA

Abstract
Laser-plasma instability is a serious concern for indirect-drive inertial confinement  fusion (ICF), where laser beams illuminate the interior of a cavity (called a hohlraum) to produce X-rays to drive the implosion of a fusion capsule. Stimulated Raman and Brillouin backscattering (SRS and SBS) could result in unacceptably high laser reflectivities. Unfortunately, it is impossible at present to fully simulate these processes realistically. Our experimental program aims to understand these instabilities by pursuing a dual strategy. (1) We use a gas-filled hohlraum  design, which best approaches ignition-hohlraum conditions, on the Nova laser  to identify important non linear trends. (2) We are shifting towards more fundamental experiments with a nearly diffraction-limited interaction laser beam illuminating extremely well characterized plasmas on the Trident laser facility at Los Alamos to probe the relevant fundamental processes.

     

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