Journal article
Energy limits of electron acceleration in the plasma sheet during substorms: A case study with the Magnetospheric Multiscale (MMS) mission
Geophysical research letters, Vol.43(15), pp.7785-7794
08/16/2016
DOI: 10.1002/2016GL069691
Abstract
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.
Key Points
Electron acceleration in substorm injections can be from a cumulative effect of a series of magnetic dipolarization events
Injected electron acceleration is most consistent with betatron acceleration over only a finite energy range, from ~10 to a few 100 keV
Injections of electrons between ~100 eV and ~10 keV result in a decrease in flux and phase space density as a function of energy
Details
- Title: Subtitle
- Energy limits of electron acceleration in the plasma sheet during substorms: A case study with the Magnetospheric Multiscale (MMS) mission
- Creators
- D. L Turner - The Aerospace CorporationA. N Jaynes - University of Colorado BoulderJ. F Fennell - The Aerospace CorporationD. N Baker - University of Colorado BoulderJ. B Blake - The Aerospace CorporationJ. H Clemmons - The Aerospace CorporationB. H Mauk - Johns Hopkins UniversityI. J Cohen - Johns Hopkins UniversityJ. V Craft - University of Colorado BoulderF. D Wilder - University of Colorado BoulderG. D Reeves - Los Alamos National LaboratoryD. J Gershman - Goddard Space Flight CenterL. A Avanov - Goddard Space Flight CenterJ. C Dorelli - Goddard Space Flight CenterB. L Giles - Goddard Space Flight CenterC. J Pollock - Goddard Space Flight CenterD Schmid - Austrian Academy of SciencesR Nakamura - Austrian Academy of SciencesR. J Strangeway - University of California, Los AngelesC. T Russell - University of California, Los AngelesA. V Artemyev - University of California, Los AngelesA Runov - University of California, Los AngelesV Angelopoulos - University of California, Los AngelesH. E Spence - University of New HampshireR. B Torbert - University of New HampshireJ. L Burch - Southwest Research Institute
- Resource Type
- Journal article
- Publication Details
- Geophysical research letters, Vol.43(15), pp.7785-7794
- DOI
- 10.1002/2016GL069691
- ISSN
- 0094-8276
- eISSN
- 1944-8007
- Number of pages
- 10
- Grant note
- NASA (NNG04EB99C)
- Language
- English
- Date published
- 08/16/2016
- Academic Unit
- Physics and Astronomy; University College Courses
- Record Identifier
- 9984199683102771
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