Collisionless magnetic reconnection: Electron processes and transport modeling

TLDR

The emphasis is on the overall evolution and particle dynamics in the diffusion region. The study derives a scaling law for how the evolution depends on current sheet width. The authors use particle‑in‑cell simulations of GEM‑challenge current sheets, extend the study to varying widths, derive a scaling law for width dependence, and compare kinetic and Hall‑MHD models. Electron distributions show nongyrotropy while ion distributions are simpler, and the kinetic–Hall‑MHD comparison reveals similar electric fields but markedly different evolution, highlighting ion pressure anisotropies. The study references the GEM magnetic reconnection challenge issue.

Abstract

Particle‐in‐cell simulations are used to investigate collisionless magnetic reconnection in thin current sheets, based on the configuration chosen for the Geospace Environment Modeling (GEM) magnetic reconnection challenge [ Birn et al. , this issue]. The emphasis is on the overall evolution, as well as details of the particle dynamics in the diffusion region. Here electron distributions show clear signatures of nongyrotropy, whereas ion distributions are simpler in structure. The investigations are extended to current sheets of different widths. Here we derive a scaling law for the evolution dependence on current sheet width. Finally, we perform a detailed comparison between a kinetic and Hall‐magnetohydrodynamic model of the same system. The comparison shows that although electric fields appear to be quite similar, details of the evolution appear to be considerably different, indicative of the role of further anisotropies in the ion pressures.