Intuitive approach to magnetic reconnection

Two reconnection problems are considered. The first problem concerns global physics. The plasma in the global reconnection region is in magnetostatic equilibrium. It is shown that this equilibrium can be uniquely characterized by a set of constraints. During reconnection and independently of the loc...

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Bibliographic Details
Published in:Physics of plasmas 2011-11, Vol.18 (11), p.111201-111201-6
Main Author: Kulsrud, Russell M.
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ABSORPTION SPECTROSCOPY
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CHARGED-PARTICLE TRANSPORT
COMPUTERIZED SIMULATION
DIFFUSION
MAGNETIC RECONNECTION
MAGNETOHYDRODYNAMICS
OHM LAW
PLASMA
PLASMA SIMULATION
SOLAR FLARES
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Summary:Two reconnection problems are considered. The first problem concerns global physics. The plasma in the global reconnection region is in magnetostatic equilibrium. It is shown that this equilibrium can be uniquely characterized by a set of constraints. During reconnection and independently of the local reconnection physics, these constraints can be uniquely evolved from any initial state. The second problem concerns Petschek reconnection. Petschek's model for fast reconnection, which is governed by resistive MHD equations with constant resistivity is not validated by numerical simulations. Malyshkin [Phys. Plasmas 12 , 102920 (2005)], showed that the reason for the discrepancy is that Petschek did not employ Ohm's law throughout the local diffusion region, but only at the X-point. A derivation of Petschek reconnection, including Ohm's law throughout the entire diffusion region, removes the discrepancy. This derivation is based largely on Petschek's original 1964 calculation [in AAS-NASA Symposium on Solar Flares (National Aeronautics and Space Administration, Washington, D.C., 1964), NASA SP50, p. 425]. A useful physical interpretation of the role which Ohm's law plays in the diffusion region is presented.
ISSN:1070-664X
1089-7674
DOI:10.1063/1.3628312