Nonlinear Absorption of Radiation by Optical Mixing in a Plasma

Abstract

Parametric excitation of longitudinal plasma oscillations can occur when a plasma is simultaneously irradiated by two laser beams whose frequencies differ by $(\frac{2}{n}){\ensuremath{\omega}}_{\mathrm{pe}}$, $n=1, 2, 3, \ensuremath{\cdots}$, where ${\ensuremath{\omega}}_{\mathrm{pe}}$ is the electron plasma frequency. We examine (i) the effect of a frequency mismatch on the excitation of the principal mode, (ii) the mode coupling in an inhomogeneous plasma, and (iii) the radiation absorption efficiencies.