Dependence of electron pressure–strain interaction on guide magnetic field for ion coupled magnetic reconnection
Journal Article
Overview
abstract
In recent years, pressure–strain interaction, which describes a pathway of internal energy evolution due to a spatially varying bulk flow, has received significant attention in collisionless magnetic reconnection. However, the influence of an out-of-plane (guide) magnetic field on the structure and amplitude of the pressure–strain interactions during reconnection has yet to be systematically explored. In this study, we use 2.5-dimensional kinetic particle-in-cell simulations of antiparallel and guide field reconnection and explore the changes due to the guide field of the electron pressure–strain interaction and its decompositions close to the X-line. We find that the structure and amplitude of the electron pressure–strain interaction for larger guide field cases differ strongly from the antiparallel case; it is non-zero over a larger region of space, and its amplitude is considerably greater when there is a guide field. It is mostly dominated by Pi−D, especially the contribution due to velocity shear. Physically, this is because in guide field reconnection, the electrons form thin current sheets along one branch of the separatrices in the exhaust region, leading to strong velocity shear. We perform a scaling analysis near the electron diffusion region in the large guide field limit to estimate the value of electron pressure–strain interaction as a function of upstream parameters for symmetric guide field reconnection and confirm the result with the simulations. We anticipate that this scaling and structure will be useful for spacecraft observations of a wide range of guide field reconnection in Earth's magnetosphere and the solar wind.
