An Improved Model for Studying the Role Played by the Trapped Particle Instability in SRS Simulations

Simulations under laser-fusion conditions have shown the potential role played by the trapped-particle instability (TPI) in saturating the non-linear evolution of Stimulated Raman Scattering (SRS). The TPI may indeed act as a secondary instability by breaking-up the primary electron plasma wave [S. Brunner and E. Valeo, Phys. Rev. Lett. {\bf 93}, 145003-1 (2004)]. First analysis of simulation results were performed using the reduced model of Kruer for the TPI [W.~L.~Kruer {\it et al.}, Phys. Rev. Lett. {\bf 23}, 838 (1969)]. An improved analysis tool has now been developed which directly implements the general linear stability theory of large BGK-like plasma waves [M. Goldman, Phys. Fluids {\bf 13}, 1281 (1970)]. The implementation of this stability analysis tool, and its application to the SRS simulation results will be presented.