Shapes of Energetic Ion Spectra in Saturn's Magnetosphere Compared with those at Earth and Jupiter

Saturn's magnetosphere contains suprathermal and energetic ions that originate from a number of plasma sources including Enceladus, Titan, Saturn's atmosphere and ionosphere and the solar wind, with internal sources dominating. Although different species originate at different locations, transport processes and acceleration during or after transport distribute the energetic ions throughout the magnetosphere out to the magnetopause. In principle, the shapes of the energy spectra of these ions contain information on acceleration processes. However, because outside of about 9 R_S long-term average spectra of all species are quite good power laws, it is difficult to pick one energy parameter (e.g., energy/charge or energy/nucleon) as better organizing the spectra by, for example, maintaining constant abundance ratios from low to high energies. Inside of 9 R_S there are energy-dependent losses that alter the spectra but aren't directly related to acceleration. Here, using data from the Cassini/CHEMS sensor, we investigate ion spectra over the energy per charge range 3-220 keV/e in more detail with better resolution in both space and time, looking for evidence of spectral differences among species based on charge (e.g., O⁺ vs. O⁺⁺) or plasma source (e.g., O⁺ (Enceladus) vs. He⁺⁺ (solar wind)). We will compare Saturn's ion spectra with those from the magnetospheres of Earth and Jupiter and discuss implications for acceleration processes.