title: Transient, small-scale field-aligned currents in the plasma sheet boundary layer during storm time substorms.
abstract: We report on field-aligned current observations by the four Magnetospheric Multiscale (MMS) spacecraft near the plasma sheet boundary layer (PSBL) during two major substorms on 23 June 2015. Small-scale field-aligned currents were found embedded in fluctuating PSBL flux tubes near the separatrix region. We resolve, for the first time, short-lived earthward (downward) intense field-aligned current sheets with thicknesses of a few tens of kilometers, which are well below the ion scale, on flux tubes moving equatorward/earthward during outward plasma sheet expansion. They coincide with upward field-aligned electron beams with energies of a few hundred eV. These electrons are most likely due to acceleration associated with a reconnection jet or high-energy ion beam-produced disturbances. The observations highlight coupling of multiscale processes in PSBL as a consequence of magnetotail reconnection.
authors.affiliation: Space Research Institute Austrian Academy of Sciences Graz Austria.
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authors.initials: R
authors.lastname: Nakamura
authors.affiliation: Earth Physics Department St. Petersburg State University St. Petersburg Russia.
authors.forename: V A
authors.initials: VA
authors.lastname: Sergeev
authors.affiliation: Space Research Institute Austrian Academy of Sciences Graz Austria.
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authors.lastname: Baumjohann
authors.affiliation: Space Research Institute Austrian Academy of Sciences Graz Austria.
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authors.lastname: Plaschke
authors.affiliation: Space Research Institute Austrian Academy of Sciences Graz Austria.
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authors.affiliation: Space Research Institute Austrian Academy of Sciences Graz Austria.
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authors.lastname: Fischer
authors.affiliation: Space Research Institute Austrian Academy of Sciences Graz Austria.
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authors.affiliation: Space Research Institute Austrian Academy of Sciences Graz Austria.
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authors.affiliation: Space Research Institute Austrian Academy of Sciences Graz Austria.
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authors.affiliation: Institute of Geophysics and Planetary Physics and Earth and Space Sciences Department University of California Los Angeles California USA.
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authors.affiliation: Institute of Geophysics and Planetary Physics and Earth and Space Sciences Department University of California Los Angeles California USA.
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authors.initials: RJ
authors.lastname: Strangeway
authors.affiliation: Institute of Geophysics and Planetary Physics and Earth and Space Sciences Department University of California Los Angeles California USA.
authors.forename: H K
authors.initials: HK
authors.lastname: Leinweber
authors.affiliation: Goddard Space Flight Center NASA College Park Maryland USA.
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authors.affiliation: Goddard Space Flight Center NASA College Park Maryland USA.
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authors.affiliation: Goddard Space Flight Center NASA College Park Maryland USA; Denali Scientific Healy Alaska USA.
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authors.lastname: Pollock
authors.affiliation: Goddard Space Flight Center NASA College Park Maryland USA.
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authors.affiliation: Goddard Space Flight Center NASA College Park Maryland USA.
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authors.initials: JC
authors.lastname: Dorelli
authors.affiliation: Goddard Space Flight Center NASA College Park Maryland USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Gershman
authors.affiliation: Goddard Space Flight Center NASA College Park Maryland USA.
authors.forename: W
authors.initials: W
authors.lastname: Paterson
authors.affiliation: Goddard Space Flight Center NASA College Park Maryland USA.
authors.forename: L A
authors.initials: LA
authors.lastname: Avanov
authors.affiliation: Southwest Research InstituteSan AntonioTexasUSA; University of Texas at San AntonioSan AntonioTXUSA.
authors.forename: S A
authors.initials: SA
authors.lastname: Fuselier
authors.affiliation: Southwest Research Institute San Antonio Texas USA.
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authors.initials: K
authors.lastname: Genestreti
authors.affiliation: Southwest Research Institute San Antonio Texas USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Burch
authors.affiliation: Southwest Research Institute San Antonio Texas USA; Physics Department University of New Hampshire Durham New Hampshire USA.
authors.forename: R B
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authors.lastname: Torbert
authors.affiliation: Physics Department University of New Hampshire Durham New Hampshire USA.
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authors.lastname: Chutter
authors.affiliation: Physics Department University of New Hampshire Durham New Hampshire USA.
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authors.lastname: Argall
authors.affiliation: Applied Physics Laboratory The Johns Hopkins University Laurel Maryland USA.
authors.forename: B J
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authors.lastname: Anderson
authors.affiliation: Space and Plasma Physics Royal Institute of Technology Stockholm Sweden.
authors.forename: P-A
authors.initials: PA
authors.lastname: Lindqvist
authors.affiliation: Space and Plasma Physics Royal Institute of Technology Stockholm Sweden.
authors.forename: G T
authors.initials: GT
authors.lastname: Marklund
authors.affiliation: Swedish Institute of Space Physics Uppsala Sweden.
authors.forename: Y V
authors.initials: YV
authors.lastname: Khotyaintsev
authors.affiliation: Applied Physics Laboratory The Johns Hopkins University Laurel Maryland USA.
authors.forename: B H
authors.initials: BH
authors.lastname: Mauk
authors.affiliation: Applied Physics Laboratory The Johns Hopkins University Laurel Maryland USA.
authors.forename: I J
authors.initials: IJ
authors.lastname: Cohen
authors.affiliation: University of Colorado Boulder Colorado USA.
authors.forename: D N
authors.initials: DN
authors.lastname: Baker
authors.affiliation: University of Colorado Boulder Colorado USA.
authors.forename: A N
authors.initials: AN
authors.lastname: Jaynes
authors.affiliation: University of Colorado Boulder Colorado USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Ergun
authors.affiliation: NOAA Space Weather Prediction Center Boulder Colorado USA.
authors.forename: H J
authors.initials: HJ
authors.lastname: Singer
authors.affiliation: Department of Climate and Space Sciences and Engineering University of Michigan Ann Arbor Michigan USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Slavin
authors.affiliation: Goddard Space Flight Center NASA College Park Maryland USA.
authors.forename: E L
authors.initials: EL
authors.lastname: Kepko
authors.affiliation: Goddard Space Flight Center NASA College Park Maryland USA.
authors.forename: T E
authors.initials: TE
authors.lastname: Moore
authors.affiliation: Centre National de la Recherche Scientifique Toulouse France.
authors.forename: B
authors.initials: B
authors.lastname: Lavraud
authors.affiliation: NASA Marshall Space Flight Center Huntsville Alabama USA.
authors.forename: V
authors.initials: V
authors.lastname: Coffey
authors.affiliation: JAXA Institute for Space and Astronautical Science Sagamihara Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Saito
keywords: MMS; PSBL; electron beam; field‐aligned currents