Kinetic Simulations of Stimulated Raman Scattering

Results of PIC simulations of the stimulated Raman scattering in one and two spatial dimensions are discussed. 2D simulation results at large kL/kD values are consistent with results by Yin et al. Phys. Plasmas 15, 013109 (2007). However, our interpretation differs in stressing the SRS reflectivity randomness due to frequency shift and transverse modulations of Langmuir waves by (i) Weibel instability due to the current of trapped particles and (ii) trapped particle modulational instability. Randomness due to the frequency shift is responsible for the first saturation of SRS. In 1D PIC simulations in inhomogeneous plasmas we have studied the interplay between trapped particle nonlinear frequency shift and plasma density inhomogeneity.