Mirror Instabilities in the Inner Magnetosphere and Their Potential for Localized ULF Wave Generation
| Autor: | Andrew J. Gerrard, Louis J. Lanzerotti, M. B. Cooper, I. V. Kuzichev, L. V. Goodwin, A. R. Soto-chavez, Hyomin Kim |
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| Rok vydání: | 2021 |
| Předmět: |
010504 meteorology & atmospheric sciences
Magnetosphere Magnetosphere: Inner Astrophysics Kinetic energy 01 natural sciences Instability Earth radius Energetic Particles: Trapped Physics::Plasma Physics inner magnetosphere Magnetospheric Physics Van Allen Probes Ionosphere magnetotail injections Anisotropy Plasma Waves and Instabilities 0105 earth and related environmental sciences Physics Magnetospheric Configuration and Dynamics Plasma ULF waves Magnetic field Geophysics mirror mode unstable plasma Space and Planetary Science Physics::Space Physics Magnetotail Research Article |
| Zdroj: | Journal of Geophysical Research. Space Physics |
| ISSN: | 2169-9402 2169-9380 |
| DOI: | 10.1029/2020ja028773 |
| Popis: | Results from the NASA Van Allen Probes mission indicate extensive observations of mirror/drift‐mirror (M/D‐M hereafter) unstable plasma regions in the night‐side inner magnetosphere. Said plasmas lie on the threshold between the kinetic and frozen‐in plasma regimes and have favorable conditions for the formation of M/D‐M modes and subsequent ultralow frequency (ULF) wave signatures in the surrounding plasma. We present the results of a climatological analysis of plasma‐γ (anisotropy measure) and total plasma‐β (ratio of particle to magnetic field pressure) in regard to the satisfaction of instability conditions on said M/D‐M modes under bi‐Maxwellian distribution assumption, and ascertain the most likely region for such plasmas to occur. Our results indicate a strong preference for the premidnight sector of the night‐side magnetosphere, with events ranging in time scales from half a minute (roughly 200 km in scale size) to several hours (multiple Earth radii). The statistical distribution of these plasma regions explicitly identifies the source region of “storm time Pc5 ULF waves” and suggests an alternative mechanism for their generation in the night‐side inner magnetosphere. Key Points Mirror mode unstable plasmas occur in the dusk‐to‐midnight inner magnetosphereMirror‐unstable plasmas are likely due to magnetotail injectionsMirror mode propagation can lead to ultra‐low frequency (ULF) mode generation |
| Databáze: | OpenAIRE |
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