Charging and coupling of a vertically aligned particle pair in the plasma sheath

Abstract

The phenomenon of particle chain formation is studied in a two-particle system. A wake of positive ions leads to an alignment of the negatively charged particles parallel to the ion flow. The dynamic response of this dust system to a small external perturbation is evaluated. It is shown that the eigenfrequency of the downstream particle is reduced compared to an isolated particle. This effect can be identified as a decharging of the particle by the focused ion flow in the wake of the upstream particle. Furthermore, a strong asymmetry of the particle interaction parallel to the ion flow is found. This asymmetry may not be attributed entirely to the interaction forces mediated by the ion wake.