NONLINEAR GENERATION OF TYPE-III SOLAR RADIO-BURSTS BY THE HYBRID MODULATIONAL INSTABILITY

An improved model of the fundamental plasma emission of type III solar radio bursts is presented. It is shown that nonlinear conversion of a traveling Langmuir pump wave into an electromagnetic wave can occur v ia either convective or absolute hybrid modulational instabilities, re sulting from the coupling of two wave triplets, with the Langmuir pump wave and ion-acoustic daughter wave common to both wave triplets. The properties of these four-wave hybrid modulational instabilities are s tudied using the observed interplanetary parameters.