HR: 08:00h
AN: SM21A-01 INVITED [PDF]
TI: Auroral particle acceleration by Alfv\'{e}n waves and ionospheric feedback
AU: * Lysak, R L
EM: bob@aurora.space.umn.edu
AF: School of Physics and Astronomy
University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 United States
AU: Song, Y
EM: yan@aurora.space.umn.edu
AF: School of Physics and Astronomy
University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 United States
AB:
Recent observations, particularly by Polar and FAST, have indicated that Alfv\'{e}n waves can directly accelerate auroral
electrons. A model for this interaction has been developed that can describe the linear modification of the Alfv\'{e}n wave
profile by the kinetic effects of electrons, including acceleration and heating of the electron population. While many of
the heated electrons are accelerated upward into the magnetosphere by the mirror force, a significant fraction of the input
Poynting flux due to Alfv\'{e}n waves can be converted into precipitating electron energy flux. An important aspect of this
particle precipitation is that the hot electrons do not arrive at the ionosphere in phase with the field-aligned current,
which at ionospheric altitudes is largely carried by cold electrons. This phase shift has direct implications for models of
ionospheric feedback that usually assume that the precipitating flux is in phase with the field-aligned current. The effects
of quasi-static electric fields can be included in the model, which will introduce new particle populations such as the
effects of secondary electrons of ionospheric origin that are reflected by the parallel potential drop. The possible role of
Alfv\'{e}n waves trapped in the ionospheric resonator in creating small-scale auroral structures through feedback and
nonlinear interactions will be discussed.
DE: 2704 Auroral phenomena (2407)
DE: 2736 Magnetosphere/ionosphere interactions
DE: 7827 Kinetic and MHD theory
DE: 7867 Wave/particle interactions
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting