Evolution of Energy Conversion and Particle Behavior in the Electron Diffusion Region During Non-Steady-State Magnetic Reconnection

Abstract

As a ubiquitous process in plasma environments, magnetic reconnection is responsible for releasing magnetic energy and energizing charged particles. However, the evolution of energy conversion and particle behavior in non-steady-state reconnection is poorly understood. Through particle-in-cell simulation, we present the energy conversion process in the electron diffusion region (EDR) during the temporal evolution of a spontaneous reconnection process under non-steady-state conditions. Our results suggest that the non-steady-state energy conversion pattern presents distinct features at different stages. Moreover, particle motions and their distributions also show various levels of anisotropy at different times. By examining the energy conversion equations and distribution functions, we show how and when electrons and ions become significantly anisotropic over time. The most drastic changes in energy conversion and particle behavior happen at the stage when the reconnection rate sharply rises; meanwhile, a large proportion of mass and energy is expelled from the EDR via enthalpy flux and bulk kinetic energy transport. Our results stress the non-steady-state nature of magnetic reconnection. These features can be vital to the development of the fast reconnection rate, which may further determine the energy conversion of the overall reconnection process.