The evolution of fast reconnection in a three-dimensional current sheet system

Journal Article · Fri Aug 15 04:00:00 EDT 2008 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2969737· OSTI ID:21120503

Ugai, M ^[1]

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1. Research Center for Space and Cosmic Evolution, Ehime University, Matsuyama 790-8577 (Japan)

By showing the details of the numerical procedure, global dynamics of the current sheet system is systematically studied by three-dimensional magnetohydrodynamic simulations in the parameter range where the numerical resistivity is much smaller than the physical resistivity. In the absence of resistivity, initiated by a reconnection disturbance, current sheet thinning drastically occurs because of the sheet pinch, leading to extreme increase in current density around the X neutral point. For the uniform resistivity model, the drastic current increase is suppressed by the magnetic diffusion (reconnection), but the reconnection jet cannot be accelerated effectively, so that any fast reconnection mechanism cannot evolve; for the smaller resistivity, the current density at the X point becomes larger. Once current-driven anomalous resistivities build up, both the reconnection flow and the anomalous resistivity simultaneously grow to enhance each other, eventually giving rise to the Alfvenic fast reconnection jet. However, if the current sheet width is smaller than three times its thickness, the fast reconnection mechanism cannot be realized even in the presence of anomalous resistivity. Hence, only when a thin current sheet of sufficiently large scale is formed in space plasmas, the fast reconnection mechanism is likely to evolve drastically, leading to distinct plasma processes responsible for flares and substorms.

• OSTI ID: 21120503
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 8 Vol. 15; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALFVEN WAVES
CURRENT DENSITY
CURRENTS
DIFFUSION
MAGNETIC RECONNECTION
MAGNETOHYDRODYNAMICS
NUMERICAL ANALYSIS
PLASMA
PLASMA SIMULATION
THREE-DIMENSIONAL CALCULATIONS