HR: 0800h
AN: SM21A-0450    [Abstracts]
TI: Upstreaming Ion Acceleration by Alfven Waves
AU: * Busch, M W
EM: busc0093@umn.edu
AF: University of Minnesota School of Physics and Astronomy, 116 Church Street SE, Minneapolis, MN 55455 United States
AU: Lysak, R L
EM: bob@aurora.space.umn.edu
AF: University of Minnesota School of Physics and Astronomy, 116 Church Street SE, Minneapolis, MN 55455 United States
AB: Spacecraft observations of the upper (~4 Earth radii) regions of auroral flux tubes have shown that the energy flux incident on the ionosphere in the form of Alfven waves is larger than the energy deposited in the aurora. Simulataneously, large fluxes of upward-moving ions are observed. Standard fluid approximations cannot explain these observations, since ion gryomotion is not included in MHD-like models. In order to study the energy transfer, a 2D auroral simulation code has been modified to include ion motion for both hydrogen and oxygen. The effect of the ions on the fields was not included. The simuations predict the observed ion energy flux and distribution. An ionospheric density cavity similar to those observed is also produced. These results suggest that the non-MHD mechanism of acceleration by parallel and perpendicular electric fields produces upward-streaming ions on auroral field lines.
DE: 2704 Auroral phenomena (2407)
DE: 2712 Electric fields (2411)
DE: 2716 Energetic particles, precipitating
DE: 2752 MHD waves and instabilities
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting