Saturn's E, G, and F rings: Modulated by the plasma sheet?

Saturn's broad E ring, the narrow G ring, and the structured and apparently time-variable F ring(s) contain many micron and submicron-sized particles, which make up the ``visible'' component. These rings (or ring systems) are in direct contact with magnetospheric plasma. Fluctuations in the plasma density and/or mean energy, due to magnetospheric and solar wind processes, may induce stochastic charge variations on the dust particles, which in turn lead to an orbit perturbation and spatial diffusion. In addition. Coulomb drag forces may be important, in particular for the E ring. The possibility that electromagnetic effects may play a role in determining the F ring structure, and it is possible time variations is critically examined. Sputtering of micron-sized dust particles in the E ring by magnetospheric ions yeilds lifetimes of 10² to 10⁴ years. This effect as well as the plasma induced transport processes require an active source for the E ring, probably Enceladus.