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Effect of the Electric Field on the Agyrotropic Electron Distributions
Author(s) -
Gao C.H.,
Tang B.B.,
Li W. Y.,
Wang C.,
Khotyaintsev Yu V.,
Graham D. B.,
Gershman D. J.,
Rager A. C.,
Giles B. L.,
Lindqvist P. A,
Ergun R. E.,
Russell C. T.,
Burch J. L.
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl091437
Subject(s) - electron , electric field , physics , gyroradius , atomic physics , computational physics , magnetopause , magnetic field , magnetosphere , quantum mechanics
We investigate agyrotropic electron distributions from two magnetopause events observed by magnetospheric multiscale (MMS) spacecraft. Agyrotropic electron distributions can be generated by the finite electron gyration at an electron‐scale boundary, and the electric field normal to this boundary usually contributes to the electron acceleration to make the agyrotropic distributions more apparent. The effect of the electric field becomes important only when it is sufficiently strong and local, meaning its electrostatic potential is comparable to or larger than the electron temperature, and its width is smaller than the electron thermal gyroradius, so that this electric field can directly accelerate part of the electrons out of the original core to form agyrotropic electron distributions. Also, we reproduce the measured electron “finger” structures from test particle simulations, which can be effectively suppressed by increasing the sampling rate of the electron measurement.