Relativistic instabilities of large amplitude waves in plasmas

Abstract

A critical review of relativistic instabilities of large amplitude electromagnetic waves in plasmas is presented. For illustrative purposes, we first summarize the small amplitude results. We then continue to take into account fully relativistic electron quiver velocity and large amplitude density fluctuations driven by a fully relativistic ponderomotive force and investigate modulational and filamentation instabilities of an intense circularly polarized electromagnetic wave. Thus, the nonlinearities arising from the relativistic electron mass variation and the relativistic ponderomotive force are treated exactly, so that our theory is valid for arbitrarily large values of the radiation intensity. Novel relativistic instabilities are shown to exist at large fluxes of the electromagnetic radiation. The relevance of our investigation to inertial confinement fusion and plasma based beat wave accelerators has been pointed out.