Ionization instability in dusty plasmas

The ionization instability in a dusty plasma in which the neutral gas is ionized by a constant flux of energetic electrons with energy slightly above the ionization energy is examined by using fluid equations for the three charged components, namely positive ions, electrons, and negatively charged dust grains. The presence of negatively charged dust increases both the frequency and the growth rate of the IA (ion-acoustic) wave excited through the ionization instability. The DA (dust-acoustic) mode, even in the absence of ion-neutral collisions, ion viscosity, and neutral gas drag on the dust grains, is always damped within the parameter ranges explored here and relevant to laboratory plasmas. The present results on the DA wave excitation are at variance with results obtained by Shukla and Morfill [Phys. Lett. A 216, 153 (1996)]. (C) 1997 American Institute of Physics.