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

TitleEnergy limits of electron acceleration in the plasma sheet during substorms: A case study with the Magnetospheric Multiscale (MMS) mission
Publication TypeJournal Article
Year of Publication2016
AuthorsTurner, DL, Fennell, JF, Blake, JB, Clemmons, JH, Mauk, BH, Cohen, IJ, Jaynes, AN, Craft, JV, Wilder, FD, Baker, DN, Reeves, GD, Gershman, DJ, Avanov, LA, Dorelli, JC, Giles, BL, Pollock, CJ, Schmid, D, Nakamura, R, Strangeway, RJ, Russell, CT, Artemyev, AV, Runov, A, Angelopoulos, V, Spence, HE, Torbert, RB, Burch, JL
JournalGeophysical Research Letters
Volume43
Issue15
Pagination7785 - 7794
Date Published08/2016
Keywordsenergetic particle injections; magnetotail; Particle acceleration; plasma sheet; reconnection; substorm; Van Allen Probes
AbstractWe 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.
URLhttp://doi.wiley.com/10.1002/2016GL069691
DOI10.1002/2016GL069691
Short TitleGeophys. Res. Lett.


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