Scaling of Magnetic Reconnection With a Limited X‐Line Extent

Abstract

AbstractContrary to all the 2‐D models, where the reconnection x‐line extent is infinitely long, we study magnetic reconnection in the opposite limit. An internal x‐line asymmetry along the current direction develops because of the transport of reconnected magnetic flux by electrons beneath the ion kinetic scale, resulting in a suppression region identified in Liu et al. (2019, https://doi.org/10.1029/2019JA026539). In this letter, we incorporate the length scale of this suppression region ≃10di to quantitatively model the reduction of the reconnection rate and the maximum outflow speed observed in the short x‐line limit. The average reconnection rate drops because of the limited active region (where the current sheet thins down to the electron inertial scale) within an x‐line. The outflow speed reduction correlates with the decrease of the J × B force, that can be modeled by the phase shift between the J and B profiles, also as a consequence of the flux transport.