THE SIMPLEST MODEL OF A DUST CLOUD IN A PLASMA

A cloud consisting of a finite number of dust grains in a plasma is co nsidered. It is shown that the absorption of the plasma by the dust gr ains gives rise to the formation of a plasma flow toward to the cloud. The drag force produced by this flow acts upon the dust grains and co unterbalances the electrostatic repulsing force. The distribution of t he grain density inside the cloud is determined. The characteristic si ze of the cloud is estimated as r(D)(3/2) / a(1/2), where r(D) is the plasma Debye radius, and a is the size of the dust grains.