Generation of stimulated backscattered harmonic radiation from intense-laser interactions with beams and plasmas.

Abstract

A comprehensive analysis is presented that describes the generation of harmonic radiation by the stimulated backscattering of intense laser fields from electron beams and from plasmas. The dynamics of the intense laser-electron interaction are analyzed using a fully nonlinear, relativistic, cold fluid model valid to all orders in the amplitude of the pump laser. In general, the backscattered radiation, from an electron beam or stationary plasma, occurs at odd harmonics of the Doppler-shifted incident laser frequency. The strength of the harmonics is strongly dependent on the incident laser intensity. The growth rate and saturation level of the backscattered harmonics are calculated, and the limitations due to thermal, space-charge, and collisional effects are discussed. Significant radiation generation at high harmonics requires sufficiently intense pump laser fields and sufficiently cold axial electron distributions. This mechanism may provide a practical method for producing coherent radiation in the xuv regime.