Cascade heating in a laser irradiated plasma

A nonlinear electromagnetic theory is developed for studying the interaction of laser radiation with the collective waves of a two-component warm plasma. Analytic expressions are obtained for steady-state (time-saturation) spectra and wave energies of the Langmuir and ion-acoustic fluctuations excited by parametric decay instabilities. The dominant nonlinear mechanism treated is the coherent excitation of secondary electrostatic waves by the Langmuir oscillation, so that the results are directly relevant when the electron temperature far exceeds the ion temperature. Threshold values for these secondary excitations are determined. Effective anomalous absorption coefficients for electrons and ions are also calculated. The nature of the depletion nonlinearity is discussed.