3-DIMENSIONAL KINEMATIC RECONNECTION OF PLASMOIDS

Kinematic reconnection of several models for three-dimensional plasmoids relevant to the solar corona and to the magnetotail is studied. The approach called kinematic reconnection, introduced in 1990 by Lau and Finn involves imposing a magnetic field and an applied inductive electric field and finding the singularities in the associated scalar potential indicating topological changes in the field line structure. These singularities mark the location of boundary layers that should be present in a self-consistent reconnection treatment. The plasmoid models introduced are called the long plasmoid, the short plasmoid, and the periodic plasmoid. In the long plasmoid, the field lines have the structure of a long arcade that has torn into plasmoids all along its length. This model has two sets of infinitely long unstable (X-type) field lines, and the singularities are located on the stable and unstable manifolds of these field lines. The short plasmoid model has behavior indicating very peaked, but not singular, current density in areas corresponding to the singularities of the long plasmoid. Thus it is possible for a short plasmoid structure to open in ideal magnetohydrodynamics. The periodic plasmoid model has singularities on a fractal set in space, indicating very complex current density structures down to the dissipation scale. The possible relevance of these results to the controversy over sheet currents and coronal heating is discussed.