Kinetic Simulations Verifying Reconnection Rates Measured in the Laboratory, Spanning the Ion-Coupled to Near Electron-Only Regimes

TL;DR

This paper uses tailored kinetic simulations to verify reconnection rates observed in TREX, confirming the transition from ion-coupled to electron-only regimes and revealing new plasma interactions.

Contribution

The study provides simulation results that accurately reproduce TREX's reconnection rates and shock conditions, advancing understanding of reconnection regimes.

Findings

Reconnection rate scales with system size as observed in TREX.

Simulations confirm shock jump conditions measured experimentally.

Identifies an interplay between reconnection layer and plasma expansion.

Abstract

The rate of reconnection characterizes how quickly flux and mass can move into and out of the reconnection region. In the Terrestrial Reconnection EXperiment (TREX), the rate at which antiparallel asymmetric reconnection occurs is modulated by the presence of a shock and a region of flux pileup in the high-density inflow. Simulations utilizing a generalized Harris-sheet geometry have tentatively shown agreement with TREX's measured reconnection rate scaling relative to system size, which is indicative of the transition from ion-coupled toward electron-only reconnection. Here we present simulations tailored to reproduce the specific TREX geometry, which confirm both the reconnection rate scale as well as the shock jump conditions previously characterized experimentally in TREX. The simulations also establish an interplay between the reconnection layer and the Alfv\'enic expansions of the background plasma associated with the energization of the TREX drive coils; this interplay has not yet been experimentally observed.