HR: 12:03h
AN: SM32A-06    [Abstracts]
TI: Electron Beams in the Jovian Magnsetosphere
AU: * Paterson, W R
EM: bill.paterson@hamptonu.edu
AF: Center for Atmospheric Sciences, Hampton University, Hampton, VA 23668 United States
AU: Frank, L A
EM: Louis-frank@Uiowa.edu
AF: Department of Physics and Astronomy, The University of Iowa, Iowa City, IA 52242 United States
AU: Ackerson, K L
EM: kent-ackerson@uiowa.edu
AF: Department of Physics and Astronomy, The University of Iowa, Iowa City, IA 52242 United States
AB: In this presentation we discuss observations of electron beams in the Jovian magnetosphere, observational constraints for heating or acceleration of electrons to produce the beams, and the significance of the beams in relationship with plasma dynamics, auroral luminosities, and magnetospheric current systems. Beams are observed in three different regions. (1) Jupiter's middle magnetosphere is threaded by beams of electrons with energies 10's of keV and likely greater. The electron distributions are field-aligned and bidirectional. These electrons may be an important seed population for more energetic distributions of electrons in the magnetosphere. They are observed at radial distances from Jupiter about 15 - 30 R_J spanning the region of the magnetosphere that is magnetically conjugate to the main ring of auroral luminosity. This also is the region where plasma motion begins to differ significantly from corotation. At Earth, upward beams of electrons are typically observed in association with regions of downward current. This may also be true at Jupiter, although the Jovian beams are observed in a region that is commonly thought to be part of an upward current system. (2) Beams with similar characteristics also are observed in association with flux-tube interchange events in the Io plasma torus, and (3) in the very near vicinity of Io where extreme mass-loading causes stagnation of plasma in Io's rest frame. Thus, the breakdown of corotation, or difference in motion compared to surrounding plasma, is a feature that may point to a common physical mechanism for the origins of these beams in three otherwise different regions.
DE: 2720 Energetic particles: trapped
DE: 2721 Field-aligned currents and current systems (2409)
DE: 2736 Magnetosphere/ionosphere interactions (2431)
DE: 2756 Planetary magnetospheres (5443, 5737, 6033)
DE: 5706 Aurorae
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005