Observation of a Source and Seed Electron Three-belt Event in the
Earth's Radiation Belts Based on Arase Satellite
Abstract
The relativistic (~500 keV–2 MeV) and
ultra-relativistic (~> 2 MeV) electron
three-belt structure can originate from the partial depletion of the
preexisting outer belt and replenishment of the new belt without direct
electron injections. These processes may be related to radial diffusion
caused by ULF (Ultra-Low Frequency) waves and local acceleration by VLF
(Very-Low Frequency) waves. In this study, we reported a three-belt
event with several hundred keV electrons based on Arase observation. The
partial depletion of the outer belt and subsequent formation of a new
belt due to source and seed electron (~30–500 keV)
injection may be the primary mechanisms responsible for the three-belt
structure. This discovery showed that the three-belt structure might not
be limited to relativistic and ultra-relativistic electrons. Our study
provided evidence for the existence of the source and seed electron
three-belt structure, which could help improve our understanding of the
radiation belt configuration.