GEM Postdoc: Nonlinear Scattering of Radiation-Belt Electrons by Chorus Waves

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Chorus is a highly non-linear whistler mode electromagnetic emission, which is excited in the low-density region exterior to the plasmapause under geo-magnetically active conditions. This important magnetospheric wave can interact with outer radiation belt electrons, causing pitch-angle scattering loss and energy diffusion. Previous calculations of the effect of wave-particle scattering has generally been performed using a quasi-linear approach. This project will quantify the effects of scattering by non-linear discrete chorus elements and compare the results with quasi-linear theory. The approach will be to carry out test particle calculations for a large number of electrons in a simulated wave field, which will be constructed including the effect of Landau damping of chorus during propagation to higher latitude. The results will subsequently be used to construct the global distribution of precipitation flux due to chorus scattering and the associated changes in ionospheric conductivity. The research is relevant to the Geospace Environment Modeling (GEM) Magnetosphere-Ionosphere coupling campaign and to the future Radiation Belt Storm Probes (RBSP) mission of National Aeronautics and Space Administration (NASA). It is also central to the Challenge "Understanding the basic physical principles manifest in processes observed in solar and space plasmas" listed in the 2002 NRC (National Research Council) Decadal Report.