Influence of Interchange on the Energetic Ion Distributions of Saturn
Abstract
Interchange injection events are a primary radial transport mechanism at Saturn, rapidly delivering energetic ions (>3 keV) to the inner and middle magnetosphere. We ask in this work: how does the global distribution of interchange injection events influence the composition and dynamics of hot ion plasma in the middle magnetosphere?
Interchange arises at Saturn due to a Rayleigh-Taylor like instability condition. The instability is caused by Saturn's rapid rotation that imparts a force outwards on the density gradient arising from Enceladus' outgassing of dense neutrals that become thermal plasma. We build off an event list detected with a trained and tested automation method developed using the CHarge Energy Mass Spectrometer (CHEMS) H+ measurements. We analyze the pitch angle and composition data of interchange events between 3 - 220 keV. Our previous work has found that interchange injection events primarily occur on the nightside. Within the nightside this distribution is asymmetric with the greatest occurrence between 7 - 9 Saturn radii in the post-midnight sector. This suggests that interchange injection events penetrate asymmetrically into the middle magnetosphere of Saturn. We investigate this by comparing the ion pitch angles and compositions within injection events, and energetic ion equatorial plasma distributions over the entire Cassini mission.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMSM52A..08A
- Keywords:
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- 2731 Magnetosphere: outer;
- MAGNETOSPHERIC PHYSICSDE: 5737 Magnetospheres;
- PLANETARY SCIENCES: FLUID PLANETSDE: 6222 Ganymede;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTSDE: 7899 General or miscellaneous;
- SPACE PLASMA PHYSICS