Electron diffusion driven by magnetospheric electrostatic waves

Abstract

The diffusion of electrons in resonance with the intense electrostatic waves recently observed on auroral lines of force is quantitatively investigated. Diffusion coefficients for scattering in both energy and pitch angle are presented as a function of electron energy and equatorial pitch angle. The results show that the waves should generally cause strong pitch angle diffusion and significant energy diffusion for electrons of energies between a few tenths and a few keV. During periods of the most intense waves observed, electrons of energies up to 100 keV can be put on strong diffusion. Measurements of 1- to 20-keV precipitating electrons made during a postbreakup aurora are found to be consistent with the pitch angle anisotropy as a function of electron energy that is predicted to result from interactions with these waves. Additional effects of the waves on the pitch angle and energy distributions of electrons are also discussed.