Energy limits of electron acceleration in the plasma sheet during substorms: A case study with the Magnetospheric Multiscale (MMS) mission

Journal Article · Mon Aug 01 00:00:00 EDT 2016 · Geophysical Research Letters

DOI:https://doi.org/10.1002/2016GL069691· OSTI ID:1340970

Turner, Drew Lawson ^[1]; Fennell, J. F. ^[1]; Blake, J. B. ^[1]; Clemmons, J. H. ^[1]; Mauk, B. H. ^[2]; Cohen, I. J. ^[2]; Jaynes, A. N. ^[3]; Craft, J. V. ^[3]; Wilder, F. D. ^[3]; Baker, D. N. ^[3]; Reeves, Geoffrey D.  ^[4]; Gershman, D. J. ^[5]; Avanov, L. A. ^[5]; Dorelli, J. C. ^[5]; Giles, B. L. ^[5]; Pollock, C. J. ^[6]; Schmid, D. ^[7]; Nakamura, R. ^[7]; Strangeway, R. J. ^[8]; Russell, C. T. ^[8] ; Artemyev, A. V. ^[8]; Runov, A. ^[8]; Angelopoulos, V. ^[8]; Spence, H. E. ^[9]; Torbert, R. B. ^[9]; Burch, J. L. ^[10]

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1. The Aerospace Corp., El Segundo, CA (United States)
2. Johns Hopkins Univ., Laurel, MD (United States)
3. Univ. of Colorado, Boulder, CO (United States)
4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
5. NASA Goddard Space Flight Center, Greenbelt, MD (United States)
6. NASA Goddard Space Flight Center, Greenbelt, MD (United States); Denali Scientific, Healy, AK (United States)
7. Austrian Academy of Sciences, Graz (Austria)
8. Univ. of California, Los Angeles, CA (United States)
9. Univ. of New Hampshire, Durham, NH (United States)
10. Southwest Research Institute, San Antonio, TX (United States)

Here, we present multipoint observations of earthward moving dipolarization fronts and energetic particle injections from NASA's 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 ~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 ~130 keV to >500 keV, with each dipolarization/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.

• Research Organization: Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: National Aeronautics and Space Administration (NASA); USDOE
• Grant/Contract Number: AC52-06NA25396
• OSTI ID: 1340970
• Report Number(s): LA-UR-16-23139
• Journal Information: Geophysical Research Letters, Vol. 43, Issue 15; ISSN 0094-8276
• Publisher: American Geophysical Union
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
heliospheric and magnetospheric physics