THE STATISTICAL-MECHANICS OF PLANETARY RI NGS FOR THE CASE OF RELATIVELY FREQUENT COLLISIONS

An approach developed in one of our previous papers is extended to the case of frequent collisions. It is shown that when there are relative ly frequent collisions, the evolution of e ring is described by the eq uations of viscous hydrodynamics. The characteristics of the quasi-sta tionary state-the components of the velocity dispersion tensor and the flux of the kinetic moment-are found for the case of arbitrary collis ion frequency. These steady-state quantities depend on certain initial ly adopted parameters of the particle collision process. The relativel y weak stability of collisions for a disk of finite thickness is estab lished as a general result.