Quasi‐linear simulations of inner radiation belt electron pitch angle and energy distributions
Abstract
“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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 24, 2016
- Source ID
- 10.1002/2016gl067938
Entities
People
- Jay M. Albert
- M. Starks
- Nigel P. Meredith
- Richard B. Horne
- Sarah A. Glauert
Organizations
- Air Force Office of Scientific Research
- Air Force Research Laboratory
- British Antarctic Survey
- National Aeronautics and Space Administration
- Natural Environment Research Council