Undriven magnetic reconnection in an isolated current sheet

Journal Article · Sat Jul 01 00:00:00 EDT 1989 · Journal of Geophysical Research; (USA)

DOI:https://doi.org/10.1029/JA094iA07p08805· OSTI ID:5830284

Scholer, M ^[1]

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1. Max-Planck-Institute 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. A spatially limited resistivity is applied in the center of the current sheet. The resistivity falls off along the current sheet with some e-folding distance x{sub l}. For sufficiently small x{sub l}, quasi-steady reconnection with a small diffusion region develops. The reconnection exhibits all Petscheklike features, such as two pairs of slow mode shocks attached to the diffusion region, a strongly converging flow toward the field line reversal region, and a weak fast mode expansion of the inflowing plasma. At larger x{sub l} values, long current sheets develop; i.e., the length of the diffusion region is always such as to occupy the largest permitted space. The flow in the long current sheet cases is also of the fast mode expansion type. However, the flow turns in these cases upstream of the separatrices into a wedge-shaped reconnection layer, whereas in the case with a small diffusion region the separatrices are well outside the reconnection layer. The reconnection rate measured in terms of the inflow Alfven Mach number well upstream of the diffusion region decreases with increasing current sheet length and reaches the Sweet-Parker rate for a current sheet corresponding to the system size. Starting the simulation with a small x{sub l} and increasing x{sub l} as a function of time to the total system size inevitably also leads to long extended current sheets with a correspondingly small reconnection rate. By artificially limiting the length of the diffusion region, the maximum reconnection rate has been determined for several simulation runs with different magnetic Reynolds numbers R{sub m}.

• OSTI ID: 5830284
• Journal Information: Journal of Geophysical Research; (USA), Journal Name: Journal of Geophysical Research; (USA) Journal Issue: A7 Vol. 94:A7; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

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71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ASTROPHYSICS
COMPUTERIZED SIMULATION
CONVERSION
CURRENTS
DIFFUSION
EARTH ATMOSPHERE
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
ENERGY CONVERSION
EXPANSION
MACH NUMBER
MAGNETIC RECONNECTION
MATHEMATICAL MODELS
PHYSICAL PROPERTIES
PLASMA
PLASMA EXPANSION
SHOCK WAVES
SIMULATION
TIME DEPENDENCE
VELOCITY