Effect of interchange instability on magnetic reconnection

Abstract

We present here the results of a study of interacting magnetic fields that involves a force normal to the reconnection layer. In the presence of such force, the reconnection layer becomes unstable to interchange disturbances. The interchange instability results in formation of tongues of heated plasma that leaves the reconnection layer through its wide surface rather than through its narrow ends, as is the case in traditional magnetic reconnection models. This plasma flow out of the reconnection layer facilitates the removal of plasma from the layer and leads to fast reconnection. The proposed mechanism provides fast reconnection of interacting magnetic fields and does not depend on the thickness of the reconnection layer. This instability explains the strong turbulence and bidirectional streaming of plasma that is directed toward and away from the reconnection layer that is observed frequently above reconnection layers. The force normal to the reconnection layer also accelerates the removal of plasma islands appearing in the reconnection layer during turbulent reconnection. In the presence of this force normal to the reconnection layer, these islands are removed from the reconnection layer by the "buoyancy force", as happens in the case of interchange instability that arises due to the polarization electric field generated at the boundaries of the islands.