Nonlinear Absorption of Radiation by Optical Mixing in a Plasma

Parametric excitation of longitudinal plasma oscillations can occur when a plasma is simultaneously irradiated by two laser beams whose frequencies differ by (2/n)ωₚₑ, n=1, 2, 3, ⋯, where ωₚₑ 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.