Reconnection in compressible plasmas: Extended conversion region
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
- NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)
The classical Sweet-Parker approach to steady-state magnetic reconnection is extended into the regime of large resistivity (small magnetic Reynolds or Lundquist number) when the aspect ratio between the outflow and inflow scale, {delta} = d/L, approaches unity. In a previous paper [Paper I, Hesse et al., Phys. Plasmas 18, 042104 (2011)], the vicinity of the dissipation site (''diffusion region'') was investigated. In this paper, the approach is extended to cover larger sites, in which the energy transfer and conversion is not confined to the diffusion region. Consistent with the results of Paper I, we find that increasing aspect ratio {delta} is associated with increasing compression, increasing reconnection rate for low {beta}, but slightly decreasing rate for higher {beta}, decreasing outflow speed, and increasing outflow magnetic field. These trends are stronger for lower {beta}. Deviations from the traditional Sweet-Parker limit {delta}{yields} 0 become significant for R{sub m}<{approx}10, where R{sub m} is the magnetic Reynolds number (Lundquist number) based on the half-thickness of the current layer responsible for the Ohmic dissipation. They are also more significant for small {gamma}, that is, for increasing compressibility. In contrast to the results of Paper I, but consistent with earlier results for {delta}<<1, we find that in this limit the outflow speed is given by the Alfven speed {nu}{sub A} in the inflow region and the energy conversion is given by an even split of Poynting flux into enthalpy flux and bulk kinetic energy flux. However, with increasing {delta} the conversion to enthalpy flux becomes more and more dominant.
- OSTI ID:
- 22047032
- Journal Information:
- Physics of Plasmas, Vol. 18, Issue 11; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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