Spatially and Chemically Segregated Energization of Jupiter's Magnetosphere
Abstract
The small-scale magnetic field fluctuations in Jupiter's middle magnetosphere undergo a turbulent cascade which transports the energy in the fluctuations to smaller length scales. This kind of turbulence is in essence a bath of weakly, but non-linearly interacting Alfven waves. The turbulent cascade is non-dissipative, but when the length scales of the fluctuations approach kinetic length scales their energy is converted into particle acceleration and heating. Key kinetic length scales for Alfvenic turbulence are the electron inertial length scale and the ion-acoustic gyroradius. We show in our presentation that the electron inertial length scale is the crucial dissipation length scale inside of 27 RJ (Jovian Radii) while the ion-acoustic gyroradius dominates outside of 27 RJ. The electron inertial length scale maximizes at the high latitudes, while the ion-acoustic gyroradius maximizes in the equatorial current sheet for the heaviest ions. This ordering implies that the Jovian magnetosphere is energized inside of 27 RJ predominantly at high latitudes where the lightest ions (i.e., protons) prevail. Outside of ~27 RJ, the heavier magnetospheric ions (i.e., sulfur) are energized in the equatorial current sheet. Observational support for this segregated energization picture comes from recent observations of energetic particles (>50 keV; Mauk et al. [2004]) which show that protons dominate the total energy flux inside of about 25 RJ and sulfur ions dominate the energy flux outside of ~25 RJ.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2004
- Bibcode:
- 2004AGUFMSM33A1254S
- Keywords:
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- 5737 Magnetospheres (2756);
- 6220 Jupiter;
- 2736 Magnetosphere/ionosphere interactions