A simulation study on reconnection and small-scale plasmoid formation

Journal Article · Wed Apr 01 04:00:00 EST 1987 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA092iA04p03223· OSTI ID:5596542

Scholer, M; Roth, D ^[1]

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1. Max-Planck-Inst. fuer Physik und Astrophysik, Garching (West Germany)

Magnetic reconnection in a plane current sheet is investigated by means of a two-dimensional time dependent compressible resistive MHD code. The system length is large compared to the current sheet half thickness. The anomalous resistivity is allowed to grow with either the electrical current density or the drift velocity. Reconnection is not forced, but is initiated by a small localized resistivity which is subsequently switched off. Fast reconnection develops self-consistently with slow shocks extending from the X point and a fast mode expansion upstream. A slow mode expansion fan leads upstream of the slow mode shocks to a plasma flow toward the X point. In the case of current dependent resistivity the reconnection rate decreases again, which leads to a flattening of the separatrices and a long current layer. Secondary tearing produces a new pair of X points which are active sites of reconnection. For low plasma {beta} the two developing plasmoids immediately merge into a single one. For high plasma {beta}, reconnection proceeds at all three X points leading to a figure-8 magnetic island structure. In the case of drift velocity dependent resistivity and low plasma {beta} values the secondary tearing occurs at locations of low density along the x axis (large resistivity). The plasmoids merge, and new X points develop further out. Continuous development of plasmoids and their subsequent coalescence leads to a large-scale plasmoid filling the whole computational box. For high plasma {beta} values (small compressibility) the resistivity (and the reconnection rate) at the initial X point stays constant, the current sheet does not elongate, and no plasmoid develops, although the system length is large. The results are discussed in relation to recent observations by ISEE 3 in the distant tail.

• OSTI ID: 5596542
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 92:A4; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
CURRENT DENSITY
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
EVALUATION
MAGNETIC BAYS
MAGNETIC RECONNECTION
MAGNETOPAUSE
MAGNETOTAIL
MATHEMATICAL MODELS
PHYSICAL PROPERTIES
PLASMA DRIFT
PLASMOIDS
SHOCK WAVES
SIMULATION