Modification of a theory of electron precipitation pulsations

Abstract

The concern of this work is to suggest some improvements in the Coroniti-Kennel theory of electron precipitation pulsations. Some inconsistencies in this theory are remedied by using the relaxation time of the electron velocity distribution as a classifying parameter. Recalculations reveal precipitation pulsations that still may be exponentially strong in the micropulsation amplitude; however, the condition for validity of this result is more restrictive than given by Coroniti and Kennel. In the transition region between weak and strong diffusion, a periodic variation in the upper cut-off frequency of the VLF spectrum may occur. This variation is in anti-phase with the whistler mode wave intensity and the magnetic perturbation causing it. In the simplified model of only parallel propagating whistler mode waves strong pitch angle diffusion probably cannot be self-excited, it must thus be of a parasitic nature.