Scaling of magnetic reconnection with a limited x-line extent

TL;DR

This paper investigates how the length of the reconnection x-line affects magnetic reconnection rates and outflow speeds, revealing asymmetries and suppression mechanisms in limited x-line scenarios.

Contribution

It introduces a model for reconnection scaling with x-line extent and identifies flux transport-induced asymmetries that suppress reconnection in short x-line limits.

Findings

Reconnection rate decreases with shorter x-line length.

Outflow speed reduction correlates with decreased J×B force.

An internal asymmetry along the current direction develops.

Abstract

Contrary to all the 2D models, where the reconnection x-line extent is infinitely long, we study magnetic reconnection in the opposite limit. The scaling of the average reconnection rate and outflow speed are modeled as a function of the x-line extent. An internal x-line asymmetry along the current direction develops because of the flux transport by electrons beneath the ion kinetic scale, and it plays an important role in suppressing reconnection in the short x-line limit; the average reconnection rate drops because of the limited active region, and the outflow speed reduction is associated with the reduction of the $J \times B$ force, that is caused by the phase shift between the J and B profiles, also as a consequence of this flux transport.