Modulational instabilities of electromagnetic waves in a collision-dominated dust-electron plasma

The nonlinear coupling between large amplitude electromagnetic waves and dust-acoustic waves (DAWs) in a dust-electron plasma is considered, taking into account the combined effects of the radiation pressure and the thermal force involving the differential Joule heating of the electrons caused by the electromagnetic waves. By employing a two-fluid approach, we derive a system of coupled equations for the electromagnetic waves and the DAWs; the latter are nonlinearly driven by the radiation and thermal forces. A normal mode analysis of our nonlinearly coupled equations is performed to obtain a general dispersion relation that is useful for studying modulational instabilities. Specific results for the latter are presented in the collision-dominated regime where the electron frequency is much larger than the DAW frequency. The implications to space plasmas are pointed out.