Limiting energy spectrum of an electron radiation belt (Invited)

Abstract:

In the last decade there has been a resurgence of radiation belt science. The NASA Van Allen Probes mission has further intensified the need to re-examine old theories and develop new theories to explain the wealth of new radiation belt particle and wave data that accumulates daily. Here we carry out a fresh examination of the Kennel-Petschek concept of self-limiting particle flux in a planetary magnetosphere. In a marginally stable state when diffusion is weak,whistler-mode waves can act to limit the trapped electron flux. Similarly,electromagnetic ion cyclotron waves can limit the stably-trapped flux of ions. In a fully relativistic regime,and without assuming in advance a particular form for the particle energy distribution,we derive an integral equation that determines the self-limiting particle flux. We obtain numerical solutions for the limiting particle spectra and compare our results with Cassini data at Jupiter and Van Allen Probes data at Earth.