Electron parametric instabilities of relativistically intense laser light in under and overdense plasma

A unified treatment of electron parametric instabilities driven by ultraintense laser light in plasma is described. The method is valid for laser light of any polarization and intensity, for any plasma density both rarefied and classically overdense, and for any scattering geometry. A fully relativistic self-consistent three-dimensional (3D) analysis, based on the cold electron fluid and Maxwell’s equations without further assumption, is carried out in the laser pulse proper frame allowing a concise description in terms of a system of six ordinary differential equations. The approach is applied to linearly polarized laser light in underdense plasma, and overdense plasma accessible by self-induced transparency. Electron charge displacement and relativistic mass fluctuations give rise to hybrids of stimulated Raman scattering, the two plasmon decay, the relativistic modulational and filamentation instabilities, and to stimulated harmonic generation. There is vigorous growth over a wide range of wave numbers and harmonics.