Dust-acoustic wave instabilities in collisional plasmas

Current-driven dust-acoustic wave instabilities in a collisional plasma wit h variable-charge dusts are studied. The effects of electron and ion captur e by the dust grains, the ion drag force, as well as dissipative mechanisms leading to changes in the particle numbers and momenta, are taken into acc ount. Conditions for the instability are obtained and discussed for both we ak and strong ion drag. It is shown that the threshold external electric fi eld driving the current is relatively large in dusty plasmas because of the large dissipation rates induced by the dusts. The current-driven instabili ty may be associated with dust cloud filamentation at the initial stages of void formation in dusty RF discharge experiments.