Physics Department Seminar University of Alaska Fairbanks

J O U R N A L    C L U B

The Aurora as a Source
for the Electron Radiation Belts
Dan Swift
Geophysical Institute, UAF

A two-dimensional particle code is used to model the propagation of Alfvén Waves on auroral field lines. When the perpendicular wavelength becomes small enough (comparable to the electron inertial length) the waves will accelerate electrons parallel to the magnetic field. This code was originally used to study the downward acceleration of electrons that might be responsible for the discrete aurora. Diagnostics show that electrons undergo multiple acceleration events. Many electrons are accelerated downward, are mirrored by the converging magnetic field and then given an upward boost by the reflected wave. The result is that upward accelerated electrons have considerably higher energies and stronger fluxes. Half of these will precipitate in the conjugate hemisphere and half will become trapped. The trapped fluxes will tend to accumulate during an acceleration event, leading to an enhanced population of trapped keV fluxes. These are the likely seed population for the electron radiation belts.

Friday, 20 April 2007
Globe Room, Elvey Building
3:45 PM