Laser Plasma Interaction Study Of Two Problems

Laser plasma interaction is a typical nonlinear problem and one of the key issues in laser fusion. The main research issues for laser plasma interaction are the propagation and absorption of the laser in plasma, parameter instabilities, the generation mechanism of super-thermal particles, etc.. The present dissertation discusses two issues in the laser plasma interaction. In the first part, we introduce the basic concepts about laser plasma interaction and simulation, and give the simulation results concerning the influence on the propagation of the laser pulse in plasma, exerted by the spatial modulation on the surface of the preformed plasma. The effect of the form of electron distribution function on electron temperature was also discussed in the first part. In the second part, starting from kinetic equations, we discussed Stimulated Raman Scattering (SRS) by including both Landau damping (LD) and the collisional damping (CD). It was found that the linear growth rate of SRS is reduced substantially due to LD and CD. SRS can occur only for a region determined by both electron temperature and density. Gap in the spectrum corresponding to Raman scattering can be explained by the present model.