Intense Laser Propagation Characteristics In Laterally Inhomogeneous Plasma

The propagation characteristics of ultra-intense short-pulse laser beams in cold underdense plasmas are studied in this dissertation. Our main work is as follows: the stable laser mode theory in uniform plasmas is extended to non-uniform plasma cases; the discussion of the sufficient and necessary conditions for laser self-focusing in uniform plasmas is developed to non-uniform plasma cases; a quantitative approach to judge the impact of different plasma density distribution on laser self-focusing is proposed; the evolution properties of asymmetric laser filed in non-uniform and uniform plasmas are discussed and mechanisms that symmetric channel-like plasmas can confine the laser centroid around the plasma channel axes and symmetrize initially asymmetric laser beams are proposed; the formation of solitary standing wave in moderate plasma density is studied by PIC simulations and can be explained by stimulated Raman scattering of laser beams in plasmas.In Chapter Ⅰ, several physical processes and features of relativistic intense laser plasma interaction are given. Besides, several simplified models of laser plasma interaction, and theoretical and numerical methods used in this dissertation are brought in.In Chapter Ⅱ, the cold one-fluid plasma model approximation, the multi-time-scale approximation, the flat-pulse approximation, the slowly-varying envelope approximation, and the quasi-static approximation are introduced. According to these approximations above, the propagation equation of laser beams in arbitrary density-distribution plasmas is simplified to a general nonlinear Schrodinger equation.In Chapter Ⅲ, we firstly study the characteristics of stable laser modes in arbitrary density-distribution plasmas. It can be shown that with the increase of the effective plasma density gradient, the critical laser power of self-focusing descends and self-focusing of laser occurs more easily. The profiles of stable modes are similar to the profiles of same-order Gaussian modes. Laser beams with more high power are...