Stress balance in Jupiter's neutral sheet
Abstract
From the time of the plasma measurements made by Voyager, there has been uncertainty about how charged particles and magnetic fields achieve force balance in the Jovian neutral sheet. Using Voyager data from the Jupiter encounters, we previously reported pressure anisotropies in the Jovian neutral sheet which added to the total particle stresses. At 3 radial distances between 15-40 Jovian radii, we found that parallel ion pressure was slightly but importantly larger than perpendicular pressure. The pressure anisotropy, along with forces associated with corotation and pressure gradients, brought the total particle forces nearly into agreement with the magnetic forces. That analysis was done using the Low Energy Charged Particle (LECP) instruments on the Voyager spacecraft. LECP detects charged particles from tens of keV to tens of MeV in energy and these have been found to significantly contribute to, if not dominate, the total plasma pressure in Jupiter's magnetosphere. The absence of ion pressure anisotropies in the Galileo Energetic Particles Detector (EPD) data from two events in which high time resolution measurements were made at comparable locations has led us to re-visit this issue in more detail. We also extend the force balance to include the region 9-15 Jovian radii using Galileo data. Developments since the original work will be discussed and magnetic energy storage will be considered.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AGUFM.P21B0373P
- Keywords:
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- 2720 Energetic particles;
- trapped;
- 2740 Magnetospheric configuration and dynamics;
- 2764 Plasma sheet;
- 5737 Magnetospheres (2756);
- 6220 Jupiter