RESUMO
Current-driven dust-acoustic wave instabilities in a collisional plasma with variable-charge dusts are studied. The effects of electron and ion capture 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 account. Conditions for the instability are obtained and discussed for both weak and strong ion drag. It is shown that the threshold external electric field driving the current is relatively large in dusty plasmas because of the large dissipation rates induced by the dusts. The current-driven instability may be associated with dust cloud filamentation at the initial stages of void formation in dusty RF discharge experiments.
RESUMO
High-frequency surface waves at the interface between two dusty plasmas subject to radiation are considered. Ultraviolet radiation with energy flux larger than the photoelectric work function of the dust surface causes photoemission of electrons. The dust charge and the overall charge balance of the plasma are thus modified. The dispersion properties of the surface waves are investigated for three parameter regimes distinguished by the charging mechanisms in the two plasmas. It is shown that photoemission can significantly affect the plasma and the surface waves.
