Weakly relativistic one-dimensional laser pulse envelope solitons in a warm plasma

Abstract

A class of exact one-dimensional solutions of coupled nonlinear equations describing the propagation of a weakly relativistic circularly polarized electromagnetic pulse in a warm, collisionless and unbounded plasma is presented. The solutions investigated are in the form of a slowly moving dark or bright envelope soliton with a propagation velocity comparable to the thermal speed of the particles. For such a slowly propagating entity, the modulational envelope is strongly modified by the effects arising due to ion inertia as well as by the thermal effects of both ions and electrons. Different regions of existence of dark and bright solitons have been identified. The analysis carried out here is restricted to nearly quasi-neutral dynamics where the second derivative term in the Poisson equation plays a subsidiary role. Under this approximation, the eigenvalue problem has continuum solutions and one can establish the nonlinear relationship between the group velocity of the soliton and the amplitude and frequency of the light pulse.