Analysis of plasma waves observed in the inner Saturn magnetosphere

Abstract. Plasma waves observed in the Saturn magneto-sphere provide an indication of the plasma population present in the rotationally dominated inner magnetosphere. Electro-static cyclotron emissions often with harmonics and whistler mode emission are a common feature of Saturn’s inner mag-netosphere. The electron observations for a region near 5RS outside and near a plasma injection region indicate a cooler low-energy (<100 eV), nearly isotropic plasma, and a much warmer (E>1000 eV) more pancake or butterfly distribution. We model the electron plasma distributions to conduct a lin-ear dispersion analysis of the wave modes. The results sug-gest that the electrostatic electron cyclotron emissions can be generated by phase space density gradients associated with a loss cone that may be up to 20 ◦ wide. This loss cone is some-times, but not always, observed because the field of view of the electron detectors does not include the magnetic field line at the time of the observations. The whistler mode emission can be generated by the pancake-like distribution and tem-perature anisotropy (T⊥/T||>1) of the warmer plasma popu-lation