J. Phys. IV France
Volume 133, June 2006
Page(s) 259 - 263
Publié en ligne 16 juin 2006
Inertial Fusion Sciences and Applications 2005
J.-C. Gauthier, et al.
J. Phys. IV France 133 (2006) 259-263

DOI: 10.1051/jp4:2006133052

Transient development of SRS and SBS in ps-time scale by using sub-ps Thomson diagnostic

C. Rousseaux1, M. Casanova1, L. Gremillet1, P. Loiseau1, M. Rabec Le Gloahec1, S.D. Baton2, F. Amiranoff2, P. Audebert2, H. Popescu2, J.C. Adam3, A. Héron3, S. Hüller3, P. Mora3 and D. Pesme3

1  Commissariat à l'Énergie Atomique, DIF, BP. 12, 91680 Bruyères-le-Châtel, France
2  LULI, UMR 7605, CNRS-CEA-École Polytechnique-Université Paris VI, École Polytechnique, 91128 Palaiseau, France
3  CPhT, École Polytechnique, 91128 Palaiseau, France

The control of parametric instabilities in large plasmas remains a challenge for the ICF program. Clearly, kinetic effects play an important role in the saturation mechanisms. Sub-picosecond Thomson analysis associated with short pulse interaction permits to explore these topics. A set of experiments have been performed in preformed, He plasmas using the 100-TW laser facility at LULI. The spectra of the electrostatic waves driven by stimulated Raman and Brillouin backscatterings generated in the 1.5 ps, ${\rm\omega} $ laser interaction have been measured with 0.3 ps time-resolution by using a short Thomson probe. Additionally, space-resolved and k-resolved spectra have been obtained. The experiments show that the fastest instability -B-SRS- first develops in the rising part of the pump. The B-SBS-driven IAW grows more slowly. B-SRS then abruptly vanishes around the maximum of the pump, while the IAW can be detected tens of picoseconds after the pump, allowing direct measurement of the IAW damping. The EPW k-spectra show that the EPW dispersion relation significantly deviates from the standard one. They exhibit a k-feature which could be related to the presence of a hot electron population produced in the B-SRS saturation process.

© EDP Sciences 2006