Charging of Dust Particles in Collisionless Plasma Sheath with Non-maxwellian Electron Energy Distribution Function

The key parameter driving behavior of dust particles in plasma is their electric charge [1]. Present-day theories as well as experiments are not fully successful in determining its value [2]. Moreover, the theoretical uncertainties are increased in the plasma sheath – a think plasma layer at a wall or electrode. The standard models of dust charging in the plasma sheath usually suppose Maxwellian electron energy distribution function (EEDF) and a flux of cold ions satisfying classical Bohm criterion. In this paper we generalize this model of plasma sheath and dust charging to arbitrary EEDF with adapted Bohm criterion. We limit our considerations to collisionless or slightly collisional plasma, when the EEDF at the plasma sheath can be derived from the EEDF calculated or measured in the plasma bulk. This possibility is of practical importance as direct measurements of EEDF in the plasma sheath are questionable.