Modelling Photoelectron Production in the Enceladus Plume and Comparison with Observations by CAPS-ELS
Abstract
The Electron Spectrometer (ELS) of the Cassini Plasma Spectrometer (CAPS) measures electrons in the energy range 0.6-28,000 eV with an energy resolution of 16.7%. ELS has observed photoelectrons produced in the plume of Enceladus. These photoelectrons are found during Enceladus encounters in the energetic particle shadow where the spacecraft is shielded from penetrating radiation by the moon [Coates et al, 2013]. Observable is a population of photoelectrons at 20-30eV, which are seen at other bodies in the solar system and are usually associated with ionisation by the strong solar He II (30.4 nm) line. We have identified secondary peaks at 40-50eV detected by ELS which are also interpreted as a warmer population of photoelectrons created through the ionisation of neutrals in the Enceladus torus. We have constructed a model of photoelectron production in the plume and compared it with ELS Enceladus flyby data using automated fitting procedures. This has yielded estimates for electron temperature and density as well as a spacecraft potential estimate which is corrected for.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMSM51E2546T
- Keywords:
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- 2704 Auroral phenomena;
- MAGNETOSPHERIC PHYSICSDE: 2731 Magnetosphere: outer;
- MAGNETOSPHERIC PHYSICSDE: 2756 Planetary magnetospheres;
- MAGNETOSPHERIC PHYSICSDE: 6222 Ganymede;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS