Stability and mass flow in Saturn's rings

Besides gravitational effects, interesting electrodynamical processes could also take place in the vicinity of the rings of Saturn. In part, this is because of the electrostatic charging of the ring particles by the magnetospheric and ionospheric plasma, and in part, the generation of impact plasma by meteoroid bombardment at the ring plane could lead to strong coupling between the rings and the ionosphere via a variety of current systems. The mass transport and angular momentum transfer in association with the ring-ionosphere coupling may cause quite large changes in the ring configuration over the age of the solar system. The presence of the sharp boundary between the B and the C rings perhaps is a good example. To highlight these new developments, we describe several of the electrodynamical mechanisms (with emphasis on their corresponding electric fields and current systems) which have been postulated to be of importance in determining the mass transport of the ring system. Further points are made that, besides mass exchange between the rings and the planetary atmosphere, the mass injection from the rings could also have significant effect on the mass and energy budget of the magnetosphere, maintenance of the E ring, the Titan hydrogen torus as well as aeronomic process in the upper atmosphere of Titan.