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

Lei Dai, Chi Wang, Suping Duan, Zhaohai He, John R. Wygant, Cynthia A. Cattell, Xin Tao, Zhenpeng Su, Craig Kletzing, Daniel N. Baker, Xinlin Li, David Malaspina, J. Bernard Blake, Joseph Fennell, Seth Claudepierre, Drew L. Turner, Geoffrey D. Reeves, Herbert O. Funsten, Harlan E. Spence, Vassilis AngelopoulosDennis Fruehauff, Lunjin Chen, Scott Thaller, Aaron Breneman, Xiangwei Tang

Research output: Contribution to journalArticle

26 Scopus citations

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 L ∼ 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 (L > 4.8). Our observations provide evidence that deep injections can supply significant MeV electrons.

Original languageEnglish (US)
Pages (from-to)6170-6179
Number of pages10
JournalGeophysical Research Letters
Volume42
Issue number15
DOIs
StatePublished - Aug 16 2015

Keywords

  • electric fields
  • radiation belt electrons
  • substorm dipolarization
  • substorm injection

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    Dai, L., Wang, C., Duan, S., He, Z., Wygant, J. R., Cattell, C. A., Tao, X., Su, Z., Kletzing, C., Baker, D. N., Li, X., Malaspina, D., Blake, J. B., Fennell, J., Claudepierre, S., Turner, D. L., Reeves, G. D., Funsten, H. O., Spence, H. E., ... Tang, X. (2015). Near-Earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations. Geophysical Research Letters, 42(15), 6170-6179. https://doi.org/10.1002/2015GL064955