Electromagnetic Turbulence in the Electron Current Layer to Drive Magnetic Reconnection

Abstract

Magnetic reconnection is a natural energy converter that can have a significant impact on global processes in space, astrophysics, and fusion plasmas. Macroscopic modeling of reconnection is crucial in understanding the global responses to local kinetic processes. The key issue in developing the reconnection model is the description of the magnetic dissipation around the x-line to drive reconnection. In collisionless plasma, the dissipation can be generated by plasma turbulence through wave–particle interactions. However, the mechanisms to yield turbulence and dissipation in the reconnection current layer are currently poorly understood. In this study, we show, using three-dimensional particle-in-cell simulations, that the electron Kelvin–Helmholtz instability plays a primary role in driving intense electromagnetic turbulence leading to the dissipation and electron heating. We find that the ions hardly react to the turbulence, which indicates that the turbulence does not cause significant momentum exchange between electrons and ions resulting in electrical resistivity. It is demonstrated that the dissipation is mainly caused by viscosity associated with electron momentum transport across the current layer. The present results suggest a fundamental modification of the current magnetohydrodynamics models using the resistivity to generate the dissipation.