J. Phys. IV France
Volume 133, June 2006
Page(s) 717 - 720
Publié en ligne 16 juin 2006
Inertial Fusion Sciences and Applications 2005
J.-C. Gauthier, et al.
J. Phys. IV France 133 (2006) 717-720

DOI: 10.1051/jp4:2006133145

Polarization smoothing on the national ignition facility

S.N. Dixit, D. Munro, J.R. Murray, M. Nostrand, P.J. Wegner, D. Froula, C.A. Haynam and B.J. MacGowan

Lawrence Livermore National Laboratory, L-462, PO Box 808, Livermore, CA 94551, USA

We have recently implemented polarization smoothing (PS) on one quad of the NIF laser. Specially cut KDP and DKDP crystals at 420 x 420 mm sizes were used to scramble the incident 351 nm laser polarization over the beam aperture. The intensity contrast deduced from the measured focal spot images for one of the NIF beams is in very good agreement with the expected contrast. KDP and DKDP crystals are known to produce considerable amount of transverse stimulated Raman scattering (SRS) when irradiated with large beams at $\sim $1-2 GW/cm2. In order to measure the transverse SRS, we attached optical fibers on the side of one of the PS crystals. The KDP PS crystal showed >1 J/cm2 side scattered SRS at irradiances of 1.2 GW/cm2. The DKDP (70% deuteration level) PS crystal showed significantly less SRS. Detailed analysis of the SRS scattering in the PS crystal is in progress.

© EDP Sciences 2006