Experimental study of the reconnection process

Abstract

We briefly review the results of a laboratory field‐line reconnection experiment. In doing so the flux transfer rate is defined and contrasted with magnetic Mach numbers as measures of the reconnection rate. We examine the origin of the reconnection electric field to determine some of the requirements of nonsteady versus steady reconnection. The dependence of various measures of the reconnection rate on electrical conductivity is discussed as well as some experimental features which may relate to previous theory. Finally, we present some approximate scaling between laboratory events and the geomagnetic substorm. We reach three major conclusions: (a) The flux transfer rate as a measure of the reconnection rate is different from a magnetic Mach number. (b) The early reconnection process is quasi‐steady state or “Petschek‐like” and we associate this phase with magnetic energy storage. A later rapid flux transfer event is more energetic and is associated with storm events. The flux transfer event is triggered by a change in resistivity. (c) The laboratory event scales reasonably well to the duration and energy of a substorm.