FUNDAMENTAL PLASMA RADIATION GENERATED BY A TRAVELING LANGMUIR WAVE -HYBRID STIMULATED MODULATIONAL INSTABILITY

A new generation mechanism for electromagnetic waves near the fundamen tal plasma frequency is discussed. It is shown that a travelling Langm uir pump wave can nonlinearly convert into electromagnetic, Langmuir a nd ion-acoustic daughter waves via a hybrid stimulated modulational in stability. The linear and nonlinear temporal dynamics of this modulati onal process involving coupling to a resonant ion-acoustic wave are st udied. The wave energy conservation relations are derived. The roles o f frequency mismatch, dissipation and wave dispersion in the temporal evolution of nonlinear coupling of two wave triplets are analysed.