Existence of Distinct Strong and Weak Shear Regimes of Self-Generated Turbulent Magnetic Reconnection
Abstract
Magnetic reconnection can become fast in three-dimensional turbulent layers. However, the parameters and mechanisms that control the fast state are not yet fully clear. Existing guide-field simulations of self-generated turbulent reconnection show locally coherent flux-rope structures embedded in a stochastic layer, motivating a flux-rope-mediated picture, with reconnection rates of order Vrec/VA ∼ 0.01 in MHD. Here, we test whether and how magnetic shear changes the reconnection regime, using 3D resistive-MHD simulations at SL=105. We vary the guide field while keeping the initial reconnecting field strength and rate normalization fixed, comparing a guide-field, weaker-shear configuration with the anti-parallel, strong-shear limit. We find that the strong-shear regime is qualitatively distinct from the flux-rope-mediated guide-field regime. Rather than retaining a narrow layer and locally coherent flux-rope structures, the current layer develops short-wavelength corrugations that broaden it substantially, and the reconnection layer electric field is sustained by fluctuation EMF. The reconnection rate increases to Vrec/VA ∼ 0.03, about three times the guide-field value. These results indicate that magnetic shear can select the mechanism controlling fast 3D turbulent reconnection, shifting the system from a guide-field regime consistent with flux-rope mediation toward a very fast turbulence-broadened regime. This transition provides a novel explanation for the sudden switch-on of fast reconnection in eruptive solar flares.
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BibTeX
@misc{ming2026existence,
title = {{Existence of Distinct Strong and Weak Shear Regimes of Self-Generated Turbulent Magnetic Reconnection}},
author = {Qihui Ming and Alexander J. B. Russell},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.09354},
eprint = {2611.09354},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.09354},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Existence of Distinct Strong and Weak Shear Regimes of Self-Generated Turbulent Magnetic Reconnection
AU - Qihui Ming
AU - Alexander J. B. Russell
PY - 2026
DA - 2026/11/06
PB - arXiv
DO - 10.48550/arxiv.2611.09354
UR - https://arxiv.org/abs/2611.09354
AB - Magnetic reconnection can become fast in three-dimensional turbulent layers. However, the parameters and mechanisms that control the fast state are not yet fully clear. Existing guide-field simulations of self-generated turbulent reconnection show locally coherent flux-rope structures embedded in a stochastic layer, motivating a flux-rope-mediated picture, with reconnection rates of order V_rec/V_A ∼ 0.01 in MHD. Here, we test whether and how magnetic shear changes the reconnection regime, using 3D resistive-MHD simulations at S_L=10^5. We vary the guide field while keeping the initial reconnecting field strength and rate normalization fixed, comparing a guide-field, weaker-shear configuration with the anti-parallel, strong-shear limit. We find that the strong-shear regime is qualitatively distinct from the flux-rope-mediated guide-field regime. Rather than retaining a narrow layer and locally coherent flux-rope structures, the current layer develops short-wavelength corrugations that broaden it substantially, and the reconnection layer electric field is sustained by fluctuation EMF. The reconnection rate increases to V_rec/V_A ∼ 0.03, about three times the guide-field value. These results indicate that magnetic shear can select the mechanism controlling fast 3D turbulent reconnection, shifting the system from a guide-field regime consistent with flux-rope mediation toward a very fast turbulence-broadened regime. This transition provides a novel explanation for the sudden switch-on of fast reconnection in eruptive solar flares.
ER -