The structure of reconnection layers: Application to the Earth's magnetopause


Using ideal magnetohydrodynamics, the structure of the reconnection layer in the Petschek reconnection model has been analyzed as a function of inflow parameters by Heyn et al. (1988). We examine the application of this analysis to conditions which are appropriate to the Earth's magnetopause. For non-antiparallel magnetic field configurations, the field rotation from one inflow region to the other is achieved through two Alfvén waves bounding the reconnection layer, although the rotation on the magnetosheath edge is much stronger. Slow shocks or slow expansion waves are needed in addition in order to form a match between the field strengths, and their appearance and strength depends on the degree of asymmetry of the inflow region parameters. Tangential velocities in the inflow regions give rise to a structure of the reconnection layer which is different above and below the reconnection line. In the presence of these tangential velocities, the Kelvin-Helmholtz stability of the magnetopause needs to be considered. If a region of the magnetopause is Kelvin-Helmholtz unstable, it is possible that Petschek-type reconnection is prevented from occurring in this region. Thus we can place constraints on the occurrence of Petschek reconnection.

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JGR: Space Physics



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