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Nongyrotropic Electrons in Guide Field ReconnectionWe apply a scalar measure of nongyrotropy to the electron pressure tensor in a 2D particle-in-cell simulation of guide field reconnection and assess the corresponding electron distributions and the forces that account for the nongyrotropy. The scalar measure reveals that the nongyrotropy lies in bands that straddle the electron diffusion region and the separatrices, in the same regions where there are parallel electric fields. Analysis of electron distributions and fields shows that the nongyrotropy along the inflow and outflow separatrices emerges as a result of multiple populations of electrons influenced differently by large and small-scale parallel electric fields and by gradients in the electric field. The relevant parallel electric fields include large-scale potential ramps emanating from the x-line and sub-ion inertial scale bipolar electron holes. Gradients in the perpendicular electric field modify electrons differently depending on their phase, thus producing nongyrotropy. Magnetic flux violation occurs along portions of the separatrices that coincide with the parallel electric fields. An inductive electric field in the electron EB drift frame thus develops, which has the effect of enhancing nongyrotropies already produced by other mechanisms and under certain conditions producing their own nongyrotropy. Particle tracing of electrons from nongyrotropic populations along the inflows and outflows shows that the striated structure of nongyrotropy corresponds to electrons arriving from different source regions. We also show that the relevant parallel electric fields receive important contributions not only from the nongyrotropic portion of the electron pressure tensor but from electron spatial and temporal inertial terms as well.
Document ID
20170001995
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Wendel, D. E.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Hesse, M.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Bessho, N.
(Maryland Univ. Greenbelt, MD, United States)
Adrian, M. L.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Kuznetsova, M.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
March 3, 2017
Publication Date
February 25, 2016
Publication Information
Publication: Physics of Plasmas
Publisher: AIP
Volume: 23
Issue: 2
Subject Category
Plasma Physics
Physics Of Elementary Particles And Fields
Report/Patent Number
GSFC-E-DAA-TN30351
Distribution Limits
Public
Copyright
Other
Keywords
Parallel Electric Fields
Nongyrotropic Electrons
Magnetic Reconnection

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