RELATIVISTIC THEORY OF WAVE-PARTICLE RESONANT DIFFUSION WITH APPLICATION TO ELECTRON ACCELERATION IN THE MAGNETOSPHERE

Resonant diffusion curves for electron cyclotron resonance with field- aligned electromagnetic R mode and L mode electromagnetic ion cyclotro n (EMIC) waves are constructed using a fully relativistic treatment. A nalytical solutions are derived for the case of a single-ion plasma, a nd a numerical scheme is developed for the more realistic case of a mu lti-ion plasma. Diffusion curves are presented for plasma parameters r epresentative of the Earth's magnetosphere at locations both inside an d outside the plasmapause. The results obtained indicate minimal elect ron energy change along the diffusion curves for resonant interaction with L mode waves. Intense storm time EMIC waves are therefore ineffec tive for electron stochastic acceleration, although these waves could induce rapid pitch angle scattering for greater than or similar to 1 M eV electrons near the duskside plasmapause. In contrast, significant e nergy change can occur along the diffusion curves for interaction betw een resonant electrons and whistler (R mode) waves. The energy change is most pronounced in regions of low plasma density. This suggests tha t whistler mode waves could provide a viable mechanism for electron ac celeration from energies near 100 keV to above 1 MeV in the region out side the plasmapause during the recovery phase of geomagnetic storms. A model is proposed to account for the observed variations in the flux and pitch angle distribution of relativistic electrons during geomagn etic storms by combining pitch angle scattering by intense EMIC waves and energy diffusion during cyclotron resonant interaction with whistl er mode chorus outside the plasmasphere.