Modification of spatial and temporal gains of stimulated brillouin and raman scattering by polarization smoothing
Significant reductions of stimulated Brillouin (SBS) and Raman (SRS) scattering are measured by adding polarization smoothing (PS) to a random phase plate smoothed beam. The associated plasma waves, as measured by Thomson scattering, are spatially and temporally modified and reveal that the interplay between SBS and SRS has to be taken into account to understand the effect of the smoothing. The results also support the numerical simulations [S. Huller et al., Phys. Plasmas 5, 2706 (1998); R. Berger et al., Phys. Plasmas 6, 1043 (1999)] predicting a reduction of self-focusing with PS, resulting in a decrease of the maximum laser intensity and consequently of SBS and SRS gains.
Fuchs
J
Laboratoire pour l'Utilisation des Lasers Intenses, UMR 7605 CNRS-Ecole Polytechnique-CEA-Universite Paris VI, Ecole Polytechnique, 91128 Palaiseau Cedex, France.
Labaune
C
Depierreux
S
Baldis
HA
Michard
A