Interaction of grains in dusty plasmas

Plasma absorption by dust grains results in anisotropy of plasma distribution function. This yields the effective attractive interaction between grains. Here a brief review of physical properties of this interaction is given. First we demonstrate that there is the attracting force between two grains obeying the inverse square low. Then a set of kinetic equations taking into account both attracting and repulsing forces is proposed. We study a simple model of a dust cloud consisting of finite number of grains. It is shown that even within gaseous approximation a dust cloud is a compact object with a sharp boundary. Finally, we discuss recent experiments aimed to detecting the attractive force between massive bodies.