Quasi-linear simulations of inner radiation belt electron pitch angle and energy distributions

Albert, Jay M.; Starks, Michael J.; Horne, Richard B. ORCID:; Meredith, Nigel P. ORCID:; Glauert, Sarah A. ORCID: 2016 Quasi-linear simulations of inner radiation belt electron pitch angle and energy distributions. Geophysical Research Letters, 43 (6). 2381-2388.

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“Peculiar” or “butterfly” electron pitch angle distributions (PADs), with minima near 90°, have recently been observed in the inner radiation belt. These electrons are traditionally treated by pure pitch angle diffusion, driven by plasmaspheric hiss, lightning-generated whistlers, and VLF transmitter signals. Since this leads to monotonic PADs, energy diffusion by magnetosonic waves has been proposed to account for the observations. We show that the observed PADs arise readily from two-dimensional diffusion at L = 2, with or without magnetosonic waves. It is necessary to include cross diffusion, which accounts for the relationship between pitch angle and energy changes. The distribution of flux with energy is also in good agreement with observations between 200 keV and 1 MeV, dropping to very low levels at higher energy. Thus, at this location radial diffusion may be negligible at subrelativistic as well as ultrarelativistic energy.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: BAS Programmes > BAS Programmes 2015 > Space Weather and Atmosphere
ISSN: 0094-8276
Additional Keywords: pitch angle distributions
Date made live: 06 Jun 2016 14:08 +0 (UTC)

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