Influence of the Hall effect on the reconnection rate at line-tied magnetic X-points
Abstract
Context: The role of the Hall term in magnetic reconnection at line-tied planar magnetic X-points is explored.
Aims: The goal is to determine the reconnection scaling laws and to investigate how the reconnection rate depends on the size of the system in Hall magnetohydrodynamics (MHD).
Methods: The evolution of reconnective disturbances is determined numerically by solving the linearized compressible Hall MHD equations. Scaling laws are derived for the decay rate as a function of the dimensionless resistivity and ion inertial length.
Results: Although the Hall effect leads to an increase in the decay rate, this increase is shown to be moderated in larger systems. A key finding is that the Hall term contribution to the decay rate, normalized by the resistive decay rate, scales inversely with the system size L, approximately as L-2.
Conclusions: The evidence suggests that decay rate enhancements due to Hall effects in line-tied X-points are weakened for large-scale systems. The result may have important implications for modeling energy release in large-scale astrophysical plasma environments, such as solar flares.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- June 2008
- DOI:
- 10.1051/0004-6361:200809569
- Bibcode:
- 2008A&A...484..847C
- Keywords:
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- magnetohydrodynamics (MHD);
- Sun: flares;
- Sun: magnetic fields