The Temperature Dependence of Plasmaspheric Ion Composition
Abstract
We examine plasmaspheric ion composition using a combination of archival and modern data. We analyze a database of Dynamics Explorer-1 (DE-1) Retarding Ion Mass Spectrometer (RIMS) densities and temperatures to yield the first explicit measure of how cold ion concentration depends on temperature. We find that cold H+ and He+ concentrations have very weak dependence on temperature, but cold O+ ion concentration increases steeply as these ions become warmer. We demonstrate how this result can aid in analyzing composition data from other satellites without spacecraft potential mitigation, by applying the result to an example using Helium Oxygen Proton Electron (HOPE) spectrometer data from the Van Allen Probes mission. Measurement of light ion concentrations above 1 eV are a reasonable proxy for the concentrations of colder (sub-eV) ions. Warmer O+ ion concentrations may be extrapolated to colder temperatures using our fit to the statistical distribution versus temperature. Finally, we show examples of composition-dependent ion pitch angle distributions that highlight the notably different pathways for light ions versus O+ to enter the plasmasphere.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSM31A..03G
- Keywords:
-
- 2431 Ionosphere/magnetosphere interactions;
- IONOSPHERE;
- 2740 Magnetospheric configuration and dynamics;
- MAGNETOSPHERIC PHYSICS;
- 2768 Plasmasphere;
- MAGNETOSPHERIC PHYSICS;
- 7845 Particle acceleration;
- SPACE PLASMA PHYSICS