Observations of Time-Domain Structures in the Plasmaspheric Plume by Van Allen Probes

Abstract

Time-domain structures (TDS), manifested as ≥ 1 ms pulses with significant parallel electric fields, play an important role in accelerating electrons in the field-aligned direction. These precipitated electrons contribute to the formation of aurora. In this study, we present observations of time-domain structures that occurred in the plasmaspheric plumes at the post-midnight to dawn sector. The close correlation between TDS and plasmaspheric plumes implies that the generation of TDS might be modulated by plasma density. During the wave occurrence, protons with an energy level below 1 keV show the enhanced field-aligned pitch-angle distributions, and the electron fluxes with the energies ranging from tens to hundreds of eV are also significantly enhanced. The correlation between TDS and scattered particles indicates the importance of including time-domain structures in future studies of radiation belt dynamics.