LONGITUDINAL-WAVES IN A DUSTY PLASMA

Longitudinal waves in a dusty plasma are studied using fluid models where we regard the dust as being immobile. The variation of the charge on the dust particles due to the wave field is taken into account. Three wave modes are considered; the ion-acoustic wave, the electrostatic ion cyclotron (EIC) wave, and the Langmuir wave. We find that the dust charge variation and the wave field have a phase shift relative to each other which influence the wave dispersion and normally lead to an energy transfer between the waves and the plasma. The low frequency longitudinal waves such as the ion-acoustic wave and EIC wave are damped, while the high frequency longitudinal Langmuir wave grows. The damping rate and the growth rate depend on the ratio between dust charge density and electron charge density, and are proportional to the dust charging frequency OMEGA(C).