A mechanism to produce a dawn-dusk component of plasma flow during magnetic reconnection in the magnetotail

Journal Article · Fri Apr 01 04:00:00 EST 1994 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/93JA02269· OSTI ID:121250

Hawkins, J G; Lee, L C; Yan, M ^[1]

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1. Univ. of Alaska, Fairbanks, AK (United States); and others

Magnetic reconnection between antiparallel field lines in the magnetotail is generally thought to produce plasma acceleration in the earthward-tailward direction. However, measurements of the plasma velocity in the magnetotail during substorm activity sometimes reveal a dawn-dusk component of plasma flow. In this paper, the authors show that a dawn-dusk component of plasma acceleration may be produced during reconnection if the neutral line is not perpendicular to the magnetic field. In this case, MHD simulations show that reconnection between antiparallel field lines will initially produce plasma acceleration that is nearly parallel to the neutral line because the magnetic tension force is not opposed by a pressure gradient force in this direction. As the magnetic field topology evolves to a steady state, the plasma flow direction rotates until it is nearly parallel to the plane that initially contained the antiparallel magnetic field lines before reconnection (hereafter referred to as the initial field plane). However, the time required to reach a steady state (typically several hundred seconds in the magnetotail region) may be greater than the time during which the reconnection process is active. Consequently, bursts of plasma flow with a dawn-dusk component may occur in the magnetotail. The initial acceleration along the neutral line depends on the angle ({theta}{sub B}) between the neutral line and the initial field plane, with the largest burst of plasma flow along the neutral line occurring when {theta}{sub B}=45{degrees}. 11 refs., 8 figs., 1 tab.

• OSTI ID: 121250
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A4 Vol. 99; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ELECTRIC CURRENTS
MAGNETIC RECONNECTION
MAGNETOTAIL
PLASMA ACCELERATION
PLASMA SHEET