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The intense populations of magnetically trap- ped, energetic charged particles that constitute the radiation belts of Saturn’s inner magnetosphere are slowly transported towards the planet by radial diffusion processes. Many of these energetic particles interact with the rings of Saturn and ultimately are lost to the magnetospheric system. Energetic protons with energies greater than ∼ 50 keV will completely penetrate ring particulates with diameters in the sub-micron regime, such as those that are key constitutents of the F, G, and E rings of Saturn. A substantial fraction of those penetrating protons (∼ 60% at 50 keV) will emerge neutralized by the interaction, ending up as hydrogen Energetic Neutral Atoms (ENAs). In this paper we document the ion⧹dust neutralization process as applied to Saturn’s inner magnetosphere and show that it is an important mechanism by which ions are lost to the magnetosphere on interacting with dust. We also show that because the dust particulates emit ENAs, the interactions between the trapped energetic particles and the ring particulates may be observed remotely by an ENA camera that measures the energy, mass species, and the arrival direction of ENAs. Such a camera, the Ion and Neutral Camera (INCA), will fly to Saturn on the Cassini spacecraft as part of the Magnetospheric Imaging Instrument (MIMI). We document the ability of the INCA sensor to use ENAs to measure the energetic-particle⧹ring particulate interactions within Saturn’s inner megnetosphere during the Saturn Orbit Insertion (SOI) phase of the Cassini mission. With such ENA images we can obtain new diagnostics of magnetospheric radial transport of energetic charged particles because the ENA intensities are proportional to these rates. Also, the impact rates for the consideration of sputtering and erosion will be better constrained, and the relative importance of the rings as a sink of radiation belt particles will be determined. Finally, the energy spectra of the ENA emissions will provide a new type of constraint on the size distribution of the ring particulates. |
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