Flow-turbulence interaction in magnetic reconnection

TL;DR

This paper explores how turbulence, especially cross helicity, interacts with flow and magnetic fields to facilitate fast magnetic reconnection, emphasizing the importance of turbulence structure and large-scale flow configurations.

Contribution

It introduces mechanisms for turbulence cross-helicity generation and analyzes their role in promoting rapid magnetic reconnection in turbulent media.

Findings

Turbulent cross helicity influences magnetic reconnection speed.

Large-scale flow and magnetic configurations support cross-helicity generation.

Turbulence and large-scale structures together facilitate fast reconnection.

Abstract

Roles of turbulence in the context of magnetic reconnection are investigated with special emphasis on the mutual interaction between flow (large-scale inhomogeneous structure) and turbulence. In order to evaluate the effective transport due to turbulence, in addition to the {\it intensity} information of turbulence represented by the turbulent energy, the {\it structure} information represented by pseudoscalar statistical quantities (helicities) is important. On the basis of the evolution equation, mechanisms that provide turbulence with cross helicity are presented. Magnetic-flux freezing in highly turbulent media is considered with special emphasis on the spatial distribution of the turbulent cross helicity. The cross-helicity effects in the context of magnetic reconnection are also investigated. It is shown that the large-scale flow and magnetic-field configurations favorable for the cross-helicity generation is compatible with the fast reconnection. In this sense, turbulence and large-scale structures promote magnetic reconnection mediated by the turbulent cross helicity.