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Title: Progress in Long Scale Length Laser-Plasma Interactions

The first experiments on the National Ignition Facility (NIF) have employed the first four beams to measure propagation and laser backscattering losses in large ignition-size plasmas. Gas-filled targets between 2 mm and 7 mm length have been heated from one side by overlapping the focal spots of the four beams from one quad operated at 351 nm (3{omega}) with a total intensity of 2 x 10{sup 15} W cm{sup -2}. The targets were filled with 1 atm of CO{sub 2} producing of up to 7 mm long homogeneously heated plasmas with densities of n{sub e} = 6 x 10{sup 20} cm{sup -3} and temperatures of T{sub e} = 2 keV. The high energy in a NIF quad of beams of 16kJ, illuminating the target from one direction, creates unique conditions for the study of laser plasma interactions at scale lengths not previously accessible. The propagation through the large-scale plasma was measured with a gated x-ray imager that was filtered for 3.5 keV x rays. These data indicate that the beams interact with the full length of this ignition-scale plasma during the last {approx}1 ns of the experiment. During that time, the full aperture measurements of the stimulated Brillouin scattering andmore » stimulated Raman scattering show scattering into the four focusing lenses of 6% for the smallest length ({approx}2 mm). increasing to 12% for {approx}7 mm. These results demonstrate the NIF experimental capabilities and further provide a benchmark for three-dimensional modeling of the laser-plasma interactions at ignition-size scale lengths.« less
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Publication Date:
OSTI Identifier:
15006528
Report Number(s):
UCRL-CONF-155301
TRN: US0400846
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: Third International Conference on Inertial Fusion Sciences and Applications, Monterey, CA (US), 09/07/2003--09/12/2003; Other Information: PBD: 11 Nov 2003
Research Org:
Lawrence Livermore National Lab., CA (US)
Sponsoring Org:
US Department of Energy (US)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; APERTURES; BACKSCATTERING; BENCHMARKS; BRILLOUIN EFFECT; FOCUSING; LASERS; LENSES; PLASMA; SCATTERING; SIMULATION; TARGETS; US NATIONAL IGNITION FACILITY