Dust particles charging in non-Maxwellian plasmas

Summary form only given, as follows. Dust contaminants play an important role in many industrial applications of plasma sciences and in space plasmas. The behaviour of dust particles immersed in plasmas is well understood in many physical situations. The charging of a dust particle under the bombardment of electrons and ions from a Maxwellian plasma has been studied in many papers. The net charge deposited on a dust particle can show fluctuations in time, but a steady state is reached. Theoretical, numerical and experimental work has shown the main features of the interactions between dust particles and Maxwellian plasmas. Recently, a number of papers have investigated with particle-in-cell (PIC) methods the details of the process of dust charging. The theoretical results have been confirmed. However, the studies, theoretical or numerical, have been limited to Maxwellian plasmas. In many physical situations this assumption is not acceptable. As an example, in many plasma-processing devices the dust particles have been shown to collect at the edge of the cathode sheath, where the ion and electron velocity distributions clearly have deviations from a Maxwellian equilibrium. In the present work we have investigated the effect of non-Maxwellian distributions and drift velocities, using simulation methods based on the PIC approach.