HR: 11:50h
AN: SM42A-07    [Abstracts]
TI: Dynamics of Relativistic Electrons Interacting With Whistler Mode Chorus Emissions in the Magnetosphere
AU: * Omura, Y
EM: omura@rish.kyoto-u.ac.jp
AF: Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Summers, D
EM: dsummers@math.mun.ca
AF: Memorial University of Newfoundland, St. John's, Newfoundland, A1C 5S7 Canada
AB: Although some of the recent studies assume that acceleration of radiation belt electrons is due to a stochastic diffusion process by broadband whistler waves, a close examination of whistler mode chorus emissions reveals that a chorus emission is a coherent monochromatic wave with a fast rising tone. The frequency of the emission increases rapidly along with growth of the wave amplitude. We first study the generation mechanism of whistler mode chorus emissions. The essential mechanism of the frequency change is critically related to the inhomogeneity of the geomagnetic field in the equatorial region. The rising tone emission is only possible, when the coherent wave propagates away from the equator interacting with a sufficient flux of counter-streaming resonant electrons. The wave growth of a rising tone can elongate the nonlinear trapping zone, which works as an effective wave train that guides a part of resonant electrons moving toward the equator. We performed test particle simulations where we solved relativistic equations of motion for high energy electrons under the electromagnetic fields of a coherent whistler mode wave and the dipole geomagnetic field. We find resonant trapping of high energy electrons by a coherent chorus emission results in efficient acceleration of the resonant particles to relativistic energy through repeated trapping processes.
DE: 2720 Energetic particles: trapped
DE: 2753 Numerical modeling
DE: 2772 Plasma waves and instabilities (2471)
DE: 2774 Radiation belts
DE: 4455 Nonlinear waves, shock waves, solitons (0689, 2487, 3280, 3285, 4275, 6934, 7851, SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005