Magnetospheric Multiscale Observations of the Source Region of Energetic Electron Microinjections Along the Duskside, High-Latitude Magnetopause Boundary Layer

Document Type

Article

Publication Date

5-16-2021

Keywords

Drift mirror instability, energetic particles, particle acceleration, particle transport, radiation belt source population

Abstract

The present paper demonstrates the first observations by the Magnetospheric Multiscale (MMS) mission of the counter-streaming energetic electrons and trapped energetic protons, localized in the magnetic field depressions between the mirror mode peaks, in the Earth's dusk sector high-latitude magnetosphere. This region is characterized by high plasma beta, strong ion temperature anisotropy, and intermediate plasma density between magnetospheric and magnetosheath plasma. We show that these plasma conditions are unstable for the drift mirror instability. The counter-streaming electron feature resembles those of the previously reported energetic electron microinjections, but without the energy-time dispersion signature. This suggests that MMS is passing through one of the potential microinjection source regions. The energetic ion data in the present study is mainly used to estimate the scale size of the mirror mode structures.

Journal Title

Geophysical Research Letters

Volume

48

Issue

9

DOI

https://doi.org/10.1029/2021GL092466

First Department

Engineering

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