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Near-Earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations
Journal article   Open access   Peer reviewed

Near-Earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations

Lei Dai, Craig Kletzing, Chi Wang, Lunjin Chen, Suping Duan, Zhaohai He, John R Wygant, Cynthia A Cattell, Xin Tao, Zhenpeng Su, …
Geophysical research letters, Vol.42(15), pp.6170-6179
08/16/2015
DOI: 10.1002/2015GL064955
PMCID: PMC5014237
PMID: 27656009
url
https://doi.org/10.1002/2015GL064955View
Published (Version of record) Open Access

Abstract

Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeVelectron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the premidnight sector at ∼ 5.5, Van Allen Probes (Radiation Belt Storm Probes)-A observed a large dipolarization electric field (50 mV/m) over ∼40 s and a dispersionless injection of electrons up to ∼3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front. Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the injections increased the MeV electron phase space density by 1 order of magnitude in less than 3 h in the outer radiation belt ( > 4.8). Our observations provide evidence that deep injections can supply significant MeV electrons.
radiation belt electrons electric fields substorm dipolarization substorm injection

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