Dust charge in the sheath of collisional low-pressure capacitive RF discharges

Abstract

Dust particles acquire electric charges by collecting electron and ion currents in plasma. These charged particles will be trapped in the sheath under some conditions. We consider the dust charge in the situation of a crystal, in which the dust particles are suspended in the collisional capacitive RF sheath at an equilibrium position. We use a cutoff like the two-temperature Maxwellian distribution to model the non-Maxwellian electron energy distribution function (EEDF) in capacitive RF discharges, and a /spl delta/ function to describe the density of dust particles; the equilibrium parameters are obtained analytically for a collisional sheath. It is found that the dust charge is very sensitive to the particle's radius, electron temperature, and ion initial velocity. The relationship between dust charge and electron temperature and the particle's radius in the sheath region is opposite to that in the plasma region.