Regulation of the Normalized Rate of Driven Magnetic Reconnection through Shocked Flux Pileup

TL;DR

This study investigates how magnetic flux pileup and shock formation influence the normalized rate of magnetic reconnection in a controlled experiment, confirming theoretical predictions and showing system size dependence.

Contribution

It demonstrates experimentally that flux pileup and shock interfaces regulate the normalized reconnection rate, validating theoretical models under asymmetric and driven conditions.

Findings

Normalized reconnection rate decreases with flux pileup.

Shock interface plays a key role in force balance during reconnection.

Reconnection rate reaches up to 0.8 at smallest system size.

Abstract

Magnetic reconnection is explored on the Terrestrial Reconnection Experiment (TREX) for asymmetric inflow conditions and in a configuration where the absolute rate of reconnection is set by an external drive. Magnetic pileup enhances the upstream magnetic field of the high density inflow, leading to an increased upstream Alfven speed and helping to lower the normalized reconnection rate to values expected from theoretical consideration. In addition, a shock interface between the far upstream supersonic plasma inflow and the region of magnetic flux pileup is observed, important to the overall force balance of the system, hereby demonstrating the role of shock formation for configurations including a supersonically driven inflow. Despite the specialised geometry where a strong reconnection drive is applied from only one side of the reconnection layer, previous numerical and theoretical results remain robust and are shown to accurately predict the normalized rate of reconnection for the range of system sizes considered. This experimental rate of reconnection is dependent on system size, reaching values as high as 0.8 at the smallest normalized system size applied.