Interactions between dust grains in a dusty plasma

Dust grains in plasma acquire a large negative charge, and can constitute a strongly coupled system. If the plasma is stationary, the plasma-mediated electrostatic potential around a single grain can be calculated by orbital- motion-limited (OML) theory, including ion absorption at the grain surface. This potential is repulsive at all ranges, and falls off as r(-2) at long range. Nonlinear modifications occur when there are several grains, but the interaction is still repulsive. If the plasma is streaming by the grains, each grain generates a wake field potential which can be calculated via lin ear response theory, and which attracts other grains to stationary points b ehind the grain. There is in addition an attractive force between grains, d ue to ion-impact momentum deposition. In certain parameter regimes, this "s hadowing" force can yield a weak net attraction at long range. Trapped-ion effects are significant at high plasma density, but have not yet been calcu lated. (C) 2000 American Institute of Physics. [S1070-664X(00)01310-0].