HR: 1340h
AN: SM13A-1189    [Abstracts]
TI: Scattering of Trapped Electrons by VLF Waves During a Magnetic Strom
AU: * Walt, M
EM: walt@nova.stanford.edu
AF: Stanford University, Starlab, Stanford, CA 94305 United States
AB: The Source/Loss Cone Energetic Particle Spectrometer (SEPS) on the NASA Polar satellite measures particle fluxes with high angular resolution (1.5 deg) near the atmospheric loss cone. During the weak magnetic storm (Dst=-40 nT) of September 10, 1996 the trapped electron fluxes increased, and the angular distributions of down-going 150 keV electrons extended well inside the atmospheric loss cone. Simultaneous measurements of up-going electrons showed empty loss cones. These loss cone fluxes were observed at MLT of ~14 hrs, latitude near 45 deg, and L between 4 and 6.5, the extent of the diffusion into the loss cone increasing with increasing L. Wave measurements with the Plasma Wave Instrument, also on the Polar satellite, showed strong VLF hiss and chorus at the time of the pitch angle diffusion. The enhanced waves and electron precipitation persisted for several days. These observations support the original Kennel and Petschek (JGR 71, 1, 1966) concept that an increase in trapped electron flux would initiate wave growth and loss of particles by pitch angle scattering. However, in this case the waves did not propagate parallel to the magnetic field and thus would couple waves and particles at different L values.
DE: 2716 Energetic particles, precipitating
DE: 2720 Energetic particles, trapped
DE: 2772 Plasma waves and instabilities
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting