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
The equilibrium, stability, and trapping of dust particles associated with vertical motions in the plasma sheath and presheath are calculated, taking into account the dependence of the variables (such as dust charge, ion flow velocity, etc.) on the local position in the sheath or presheath region of a collisional plasma with an ionization source. It is demonstrated that an increase of the rate of ionization considerably influences the equilibrium positions of dust grains, shifting them toward the electrode as well as increasing the maximum possible (equilibrium) levitation grain size.
