The nonlinear interaction of relativistic laser and hot plasma

Propagation of an electromagnetic (EM) pulse in an underdense plasma can either generate a wakefield or excite soliton wave, which depends on the competition between the linear dispersion and nonlinear self-modulation of the wave. Here, we study the interaction of the EM pulse and relativistic hot plasma analytically and numerically and reveal the physical mechanism of the transition from wakefield generation to soliton excitation in terms of soliton stability and modulation instability (MI) of a plane wave. Starting from the relativistic hot fluid-Maxwell model, a nonlinear Schrodinger equation (NLSE) governing the amplitude of scalar potential is obtained by using a multi-scale perturbation technique. The bright and dark soliton solutions of the NLSE are obtained analytically. The stability phase diagram of solitons is given numerically. Furthermore, the MI of the plane wave is studied, and the stability phase diagram of MI is obtained. The results indicate that, when the plasma density increases, the propagation of the EM pulse in the plasma experiences wakefield-soliton transition, which depends on the thermal effect. Our results provide theoretical evidence for deep understanding of high-power laser plasma interaction.