The Plasma Proton Environment within Saturn's inner magnetosphere as Observed by the Cassini Plasma Spectrometer (CAPS) during Saturn Orbit Insertion
Abstract
In analyzing the Cassini data between Saturn's A-ring outer edge and Mimas' L shell numerous inconsistencies have been reported in estimates of total ionic charge and electron density. The primary focus of our work is to understand these inconsistencies. We present our recent discovery of plasma protons during Saturn Orbit Insertion (SOI) outbound pass of the magnetospheric region between the F and G rings. We also searched for H2+ ions but no such events were found. The discovery of protons was made possible by a recent analysis of the CAPS Ion Mass Spectrometer's (IMS's) time-of-flight (TOF) composition data in a mode of reduced post-acceleration voltage at 6 kV instead of the usual 14.6 kV. All previous work for this region had not considered the TOF data. The new proton analysis was enabled by minimum scattering of 6 kV protons in the instrument's ultrathin carbon foils (CF), in comparison to larger scattering for the heavier ions such as for O+ and O2+. We use a SIMION model of the CAPS IMS including the effects of energy straggling and scattering by the instrument's CFs in an attempt to understand the TOF composition data for the heavier ions. This analysis within the uncertainties of the instrument allows us to estimate the relative abundances of the heavier ions and thus run our 2D velocity ion moments code to get ion densities, temperatures and velocities during the SOI outbound pass through the F-ring and G-ring gap. Comparisons with other data sets will be made.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFMSM33C2692S
- Keywords:
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- 5719 Interactions with particles and fields;
- PLANETARY SCIENCES: FLUID PLANETS;
- 5737 Magnetospheres;
- PLANETARY SCIENCES: FLUID PLANETS;
- 6299 General or miscellaneous;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 7899 General or miscellaneous;
- SPACE PLASMA PHYSICS