Collisionless magnetic reconnection: Electron processes and transport modeling

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 [B irn 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 distributi ons are simpler in structure. The investigations are extended to current sh eets of different widths. Here we derive a scaling law for the evolution de pendence on current sheet width. Finally, we perform a detailed comparison between a kinetic and Hall-magnetohydrodynamic model of the same system. Th e 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.