A Kinetic Model for Electron Heating in Antiparallel Magnetic Reconnection Exhausts

In antiparallel reconnection, parallel beams of cold electrons are often seen streaming into the reconnection region, accelerated inward by a parallel potential. We investigate a method of electron bulk heating wherein energy is exchanged through the parallel potential into bulk streaming energy in beams and is then thermalized through an effective scattering process. This scattering process is based on the breakdown of the electron magnetic moment as an adiabatic invariant in the reconnection exhaust, which causes the distribution to be independent of the magnetic moment in that region. A simplified differential equation has been derived to explain this thermalization. Results from VPIC simulations designed to provide constraints for two model parameters related to the efficiency of first- and second-order Fermi acceleration across a range of upstream conditions will be presented. This model retains first-order parallel electron dynamics and can be extended to a scale-invariant model applicable to large-scale systems that are not amenable to kinetic simulation, such as the solar corona.