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Electromagnetic hybrid‐code simulation of magnetic reconnection: Velocity distribution functions of accelerated ions
Author(s) -
Nakabayashi J.,
Machida S.
Publication year - 1997
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 - 10.1029/97gl01206
Subject(s) - electric field , plasma sheet , physics , current sheet , plasma , magnetic reconnection , computational physics , plasmoid , particle acceleration , field (mathematics) , diffusion , magnetic field , atomic physics , mechanics , magnetosphere , magnetohydrodynamics , quantum mechanics , mathematics , pure mathematics
A 2‐1/2 dimensional electromagnetic hybrid simulation was conducted to explore particle acceleration in the magnetic reconnection process in the Earth magnetotail. By adding a localized anomalous resistivity to the neutral sheet of initial static Harris solution, we realized a spontaneous magnetic reconnection. We found that two kinds of characteristic electric fields were generated in addition to the conventional dawn‐to‐dusk electric field after the reconnection commenced. The first type of the electric field is directed toward the neutral sheet in the expanded plasma sheet boundary layer (PSBL), resulting in a dawnward drift of cold ions. The second type of electric field was directed as the conventional dawn to dusk component in the plasma sheet, but with a significantly large component away from the diffusion region. Though well‐developed slow mode shocks were not formed, this field played a significant role in plasma jet formation. The energy transfer from the electric field to the ions with the first type electric field was three times higher than with that the second type field. In addition to these perpendicular electric fields, the field‐aligned electric field in front of expanding plasma sheet (early‐phase plasmoid) caused a parallel ion acceleration. The dawnward plasma drift in the expanded plasma sheet and PSBL yielded a nonzero B y field whose polarity showed an octupole structure with respect to the central diffusion region. The relevant forms of ion distribution functions predicted by the present model are also considered in this study. This model can be applied to the transient phase of the magnetic reconnection, i.e., the expansion phase of the magnetospheric substorms.