Electron beams as the source of whistler‐mode auroral hiss at Saturn

Abstract

Over the last three years, the Cassini spacecraft has been in a series of high inclination orbits, allowing investigation and measurements of Saturnian auroral phenomena. During this time, the Radio and Plasma Wave Science (RPWS) Investigation on Cassini detected low frequency whistler mode emissions propagating upward along the auroral field lines, much like terrestrial auroral hiss. Comparisons of RPWS data with Cassini Plasma Spectrometer (CAPS) plasma measurements during a high‐latitude pass on 17 October 2008, show that intense upward moving electron beams with energies of a few hundred eV were associated with auroral hiss emissions. In this paper we show that these beams produce large growth rates for whistler‐mode waves propagating along the resonance cone, similar to the generation of auroral hiss at Earth.