HR: 0800h
AN: SM51A-1267    [Abstracts]
TI: Modeling of Triggered Emissions Using Pitch Angle Diffusion
AU: * Gibby, A
EM: argibby@stanford.edu
AF: STAR Laboratory, Stanford University, Packard Bldg 350 Serra Mall , Stanford, CA 94305 United States
AU: Inan, U S
EM: inan@nova.stanford.edu
AF: STAR Laboratory, Stanford University, Packard Bldg 350 Serra Mall , Stanford, CA 94305 United States
AU: Bell, T F
EM: bell@nova.stanford.edu
AF: STAR Laboratory, Stanford University, Packard Bldg 350 Serra Mall , Stanford, CA 94305 United States
AB: The utilization of a diffusion model for pitch angle scattering of radiation belt particles by wide-band whistler mode turbulence has been recognized for some time. Historically, though, the use of a diffusion model to describe the interaction with coherent waves and subsequent emissions has been considered inappropriate due to the nonlinear and highly coherent nature of these interactions. However, if appropriate modifications to the model are made to reflect the nearly-monochromatic nature of the triggering signal, a diffusion-based model offers the dual advantages of being computationally simpler than full-particle models while also allowing the inclusion of the effects of a full distribution of particles in the triggering process. The method described herein concentrates on the modeling of wave growth in a region near the geomagnetic equator, where the growth rate is fundamentally determined by the anisotropy of the equatorial particle distribution. Subsequent pitch angle scattering of particles is modeled by pitch angle scattering of the equatorial distribution with appropriately determined diffusion coefficients. Despite the rudimentary nature of this model, it predicts some of the qualitative characteristics of triggered emissions, such as: growth above the triggering frequency, suppression of signals closely spaced in frequency, the generation of a "quiet band" below the triggering frequency, and rising emissions from a continuous wave source.
DE: 7867 Wave/particle interactions (2483, 6984)
DE: 7868 Wave/wave interactions
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005