Energy Budgets From Collisionless Magnetic Reconnection Site to Reconnection Front

Abstract

AbstractCollisionless magnetic reconnection occurs ubiquitously in space plasma environments and plays an important role in energy conversion therein. In collisionless magnetic reconnection, the reconnection site is usually unsteady and ejects reconnection fronts away from it. Using two‐dimensional particle‐in‐cell simulations, we study the energy budgets from the collisionless magnetic reconnection site to reconnection fronts. It is concluded that the reconnection rate cannot well reflect energy conversion of nonsteady state magnetic reconnection because energy conversion occurs predominantly at the reconnection fronts, whereas the reconnection rate can only represent the energy conversion at the reconnection site. We clarify the connection between the reconnection site and the reconnection fronts in terms of energy conversion. The reconnection site functions as a trigger and energy source that generates the outflow of Poynting flux, bulk kinetic energy flux, and enthalpy flux forming the reconnection fronts that move downstream. The well‐developed reconnection fronts are no longer related to the reconnection site. The energy income at the reconnection fronts is mainly the Poynting flux from their top and bottom boundaries, most of which is transformed to flux flowing downstream out of the moving front through the work by the electric field. The work done by the electric force is compensated with the work done by the thermal pressure gradient, which guarantees that the released magnetic energy is mostly converted to thermal energy.