HR: 0830h
AN: SM41B-0569    [PDF]
TI: Perpendicular Heating of H$^{+}$ and O$^{+}$ Ions Due to an Oblique Double Layer at the Transition Region of the Auroral Cavity
AU: * Main, D S
EM: daniel.main@colorado.edu
AF: Laboratory for Atmospheric and Space Physics, 1234 Innovation Dr., Boulder, Co 80303-7814 United States
AU: Ergun, R
EM: ree@fast.colorado.edu
AF: Laboratory for Atmospheric and Space Physics, 1234 Innovation Dr., Boulder, Co 80303-7814 United States
AU: Andersson, L
EM: andersson@lasp.colorado.edu
AF: Laboratory for Atmospheric and Space Physics, 1234 Innovation Dr., Boulder, Co 80303-7814 United States
AB: The acceleration mechanism of the precipitating electrons associated with the visible aurora is investigated in this paper. These precipitating electrons form in the upward current region of the auroral cavity, a region separating the magnetosphere and the ionosphere. There are several possible mechanisms that may contribute to electron acceleration. One possible cause of electron acceleration is quasi-static, parallel electric fields, which have been observed in the auroral cavity. Recent research has shown that the auroral cavity may have two boundaries associated with it: one between the ionosphere and the auroral cavity and the other between the magnetosphere and the auroral cavity. We present work that explores the boundary between the ionosphere and the auroral cavity known as the lower transition region. Observations suggest that this lower boundary may be an oblique double layer, which is the cause of the quasi-static parallel electric field. Using test particle simulations we explore the effects on distributions of weakly magnetized O$^{+}$ ions and moderately magnetized H$^{+}$ ions. The observed width of the oblique double layer is much greater than the H$^{+}$ gyro-radius but on the same order as O$^{+} $gyro-radius. Therefore, we expect the O$^{+}$ distribution to be heated more than the H$^{+}$distribution in the direction perpendicular to the magnetic field. This may partially explain the distributions of ion beams observed at higher altitudes.
DE: 2704 Auroral phenomena (2407)
DE: 2712 Electric fields (2411)
DE: 2736 Magnetosphere/ionosphere interactions
DE: 2753 Numerical modeling
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting