Generation of near-Earth reconnection by divergent flows in the plasma sheet

Abstract

A global two-dimensional hybrid simulation is carried out to study the evolution of the near-Earth plasma sheet. It is shown that reconnection X lines and plasmoids can be generated by diverging flows in the plasma sheet. These diverging flows can be caused by variations in the Maxwell stress due to variations of B-x and B-z components of the magnetic field outside the current sheet. In addition, the flow acceleration/deceleration in the plasma sheet can also be caused by variations in the local plasma mass density. Comparison runs have been made with a Harris model current sheet with zero B-z, and no evidence of reconnection is found. The results indicate that divergent plasma flow is a sufficient condition for reconnection even in a dissipation-less plasma.