University of Maryland
Electron Heating and Acceleration in Collisionless Magnetic Reconnection
We explore electron acceleration in collisionless magnetic reconnection via particle-in-cell (PIC) simulations with non-zero guide fields so that electrons remain magnetized. We address two important sources of particle energization: electric fields parallel to the magnetic field, and electric fields parallel to the curvature-drift (the latter associated with acceleration by Fermi reflection). In the case of a small guide field (20% of the magnitude of the reconnecting field) the curvature drift is the dominant source of electron heating, while for a larger guide field (equal to the magnitude of the reconnecting component) the electron acceleration by the curvature drift is comparable to that of the parallel electric field. We find that in both simulations, acceleration at high electron energies is primarily due to the curvature-drift, which suggests that this mechanism may be more important for the generation of energetic (nonthermal) electrons. Additionally, the acceleration due to the curvature-drift occurs over a large area, whereas the parallel electric field is localized near X-lines. This suggests that acceleration by parallel electric fields may play a smaller role in large physical systems, such as the solar corona, where the X-line occupies a vanishing fraction of the system.