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Energy Limits of Electron Acceleration in the Plasma Sheet During Substorms: A Case Study with the Magnetospheric Multiscale (MMS) MissionWe present multipoint observations of earthward moving dipolarization fronts and energetic particle injections from NASAs Magnetospheric Multiscale mission with a focus on electron acceleration. From a case study during a substorm on 02 August 2015, we find that electrons are only accelerated over a finite energy range, from a lower energy threshold at approx. 7-9 keV up to an upper energy cutoff in the hundreds of keV range. At energies lower than the threshold energy, electron fluxes decrease, potentially due to precipitation by strong parallel electrostatic wavefields or initial sources in the lobes. Electrons at energies higher than the threshold are accelerated cumulatively by a series of impulsive magnetic dipolarization events. This case demonstrates how the upper energy cutoff increases, in this case from approx. 130 keV to >500 keV, with each depolarization/injection during sustained activity. We also present a simple model accounting for these energy limits that reveals that electron energization is dominated by betatron acceleration.
Document ID
20170003545
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Turner, D. L. (Aerospace Corp. El Segundo, CA, United States)
Fennell, J. F. (Aerospace Corp. El Segundo, CA, United States)
Blake, J. B. (Aerospace Corp. El Segundo, CA, United States)
Clemmons, J. H. (Aerospace Corp. El Segundo, CA, United States)
Mauk, B. H. (Johns Hopkins Univ. Laurel, MD, United States)
Cohen, I. J. (Johns Hopkins Univ. Laurel, MD, United States)
Jaynes, A. N. (Colorado Univ. Boulder, CO, United States)
Craft, J. V. (Colorado Univ. Boulder, CO, United States)
Wilder, F. D. (Colorado Univ. Boulder, CO, United States)
Baker, D. N. (Colorado Univ. Boulder, CO, United States)
Reeves, G. D. (Los Alamos National Lab. NM, United States)
Gershman, D. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Avanov, L. A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Dorelli, J. C. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Giles, B. L. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Pollock, T. C. (Denali Scientific, LLC Healy, AK, United States)
Schmid, D. (Space Research Inst. Graz, Austria)
Nakamura, R. (Space Research Inst. Graz, Austria)
Strangeway, R. J. (California Univ. Los Angeles, CA, United States)
Russell, C. T. (California Univ. Los Angeles, CA, United States)
Artemyev, A. V. (California Univ. Los Angeles, CA, United States)
Runov, A. (California Univ. Los Angeles, CA, United States)
Angelopoulos, V. (California Univ. Los Angeles, CA, United States)
Spence, H. E. (New Hampshire Univ. Durham, NH, United States)
Torbert, R. B. (New Hampshire Univ. Durham, NH, United States)
Burch, J. L. (Southwest Research Inst. San Antonio, TX, United States)
Date Acquired
April 17, 2017
Publication Date
August 1, 2016
Publication Information
Publication: Geophysical Research Letters
Volume: 43
Issue: 15
ISSN: 0094-8276
Subject Category
Space Sciences (General)
Report/Patent Number
GSFC-E-DAA-TN40977
Funding Number(s)
CONTRACT_GRANT: NNG04EB99C
Distribution Limits
Public
Copyright
Other