Simulation of charging and shielding of dust particles in drifting plasmas

To understand the process of dust charging and shielding, self-consistent kinetic simulations are conducted using the Particle-In-Cell method to describe the plasma species, and the immersed boundary method to describe the plasma-dust interactions. The effect of a relative flow between the ions and the dust particles is considered in conditions similar to the real configuration of plasma reactors used in semiconductor manufacturing and in dusty plasma crystal experiments. The ion flow is found to induce changes in the equilibrium dust charge and in the shielding cloud. The ion flow causes a downstream potential wake. For dielectric dust particles, the ion flow has the additional effect of producing nonuniform charge distributions on the dust surface and multipolar components in the shielding potential. Comparisons with existing theories show sufficient accuracy of the orbit motion limited theory to determine the equilibrium charge. Instead, the linear theories for the Debye shielding are insufficient in some respects. Comparisons with experimental observations confirm the conclusions of the simulations. (C) 1999 American Institute of Physics. [S1070-664X(99)04205-6].