The effects of a double pulse of reconnection in a non-uniform magnetic field configuration

Abstract

We present a time-dependent analysis of reconnection in a non-uniform magnetic field geometry, based on a Petschek-type reconnection model valid for an incompressible plasma. The initial two-dimensional magnetic field configuration consists of a Y-type magnetic field distribution. We have performed the analysis using frozen-in coordinates, which provide a reference frame co-moving with magnetic flux tubes; the introduction of these coordinates simplifies the calculations considerably. The analysis allows us to determine the time evolution of the system when subjected to two successive pulses of reconnection. The large-scale structures which appear differ considerably from those found in the case of reconnection in a uniform magnetic field configuration, and we point out the major differences. We also find that the leading part of the structure launched as a result of the second pulse of reconnection catches up with the trailing part of the first structure, and the two start to interact with each other. Possible application of the results presented here include the cusp region in the terrestrial magnetosphere.