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

Journal Article · Mon Aug 10 00:00:00 EDT 2015 · Geophysical Research Letters

DOI:https://doi.org/10.1002/2015GL064955· OSTI ID:1212461

Dai, Lei ^[1]; Wang, Chi ^[2]; Duan, Suping  ^[2]; He, Zhaohai ^[2]; Wygant, John R. ^[3]; Cattell, Cynthia A. ^[3]; Tao, Xin ^[4]; Su, Zhenpeng  ^[4]; Kletzing, Craig ^[5]; Baker, Daniel N. ^[6]; Li, Xinlin ^[6]; Malaspina, David  ^[6]; Blake, J. Bernard ^[7]; Fennell, Joseph ^[7]; Claudepierre, Seth ^[7]; Turner, Drew L. ^[7]; Reeves, Geoffrey D.  ^[8]; Funsten, Herbert O. ^[8]; Spence, Harlan E. ^[9]; Angelopoulos, Vassilis ^[10] ; Fruehauff, Dennis  ^[11]; Chen, Lunjin ^[12]; Thaller, Scott ^[3]; Breneman, Aaron ^[3]; Tang, Xiangwei ^[3]

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1. Chinese Academy of Sciences, Beijing (China). State Key Lab. of Space Weather, National Space Science Center; Univ. of Minnesota, Twin Cities, Minneapolis, MN (United States). School of Physics and Astronomy.
2. Chinese Academy of Sciences, Beijing (China). State Key Lab. of Space Weather, National Space Science Center
3. Univ. of Minnesota, Twin Cities, Minneapolis, MN (United States). School of Physics and Astronomy.
4. Univ. of Science and Technology of China, Hefei (China). Dept. of Geophysics and Planetary Sciences.
5. Univ. of Iowa, Iowa City, IA (United States). Dept. of Physics and Astronomy.
6. Univ. of Colorado Boulder, Boulder, CO (United States). Lab. for Atmospheric and Space Physics.
7. The Aerospace Corporation, Los Angeles, CA (United States). Space Sciences Dept.
8. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
9. Univ. of New Hampshire, Durham, NH (United States). Dept. of Physics Institute for Earth, Oceans and Space.
10. Univ. of California, Los Angeles, CA (United States). Dept. of Earth, Planetary and Space Sciences and Institute of Geophysics and Planetary Physics.
11. Braunschweig University of Technology, Braunschweig (Germany). Institute of Geophysics and extraterrestrial Physics.
12. University of Texas at Dallas, Richardson, TX (United States). Department of Physics.

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.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC52-06NA25396; 41231067; 921647; NNX15AF55G
• OSTI ID: 1212461
• Alternate ID(s): OSTI ID: 1234256
• Report Number(s): LA-UR-15-27791
• Journal Information: Geophysical Research Letters, Journal Name: Geophysical Research Letters; ISSN 0094-8276
• Publisher: American Geophysical Union
• Country of Publication: United States
• Language: English

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