Influence of charge variation on particle oscillations in the plasma sheath

The theory of dust particle oscillations in the plasma sheath is presented, taking into account particle charging kinetics and neutral gas friction. Effects of ''regular'' and stochastic charge variations are considered. It is shown that whilst regular variations generally enhance the damping of horizontally propagating dust lattice waves, they can also cause an instability in the vertical oscillations of single particles. The stochastic charge variations, if sufficiently strong, result in exponential growth of the mean energy of both types of oscillations.