EVIDENCE OF A SOURCE OF ENERGETIC IONS AT SATURN

We calculate phase space densities, in terms of adiabatic invariants o f charged particle motion, using the low-energy char,oed particle (LEC P) data from the Voyager 2 encounter with Saturn. Ion data are correct ed for electron contamination. For all energies considered here, phase space density at fixed first and second adiabatic invariant, f(L), in creases with increasing equatorial pitch angle. Evidence exists for a source of low-energy ions (similar to 0.07-4.2 MeV) and energetic prot ons (54-152 MeV) close to Saturn. The source of >50 MeV protons is lik ely to be cosmic ray albedo neutron decay (GRAND), although we know of no source mechanism for the low-energy ions. Low-energy ion phase spa ce densities calculated here have characteristics of solutions of a st eady-state radial diffusion equation with sources outside the region o f interest and near Saturn and losses. Losses are attributed to satell ites, rings, and Saturn's atmosphere and observed changes in f with re spect to the adiabatic invariants of motion are consistent with model loss rates in most cases. For energetic protons mirroring near the mag netic equator, phase space densities are in good qualitative agreement with other analyses of Pioneer 11 and Voyager 2 Cosmic Ray System (CR S) data indicating a likely GRAND source close to Saturn and absorptio n by Mimas. Voyager data phase space densities for GRAND protons that mirror off the magnetic equator are presented for the first time. An e stimate of the upper limit on average G ring particulate size of simil ar to 1 cm is described.