Entropy production and transport during magnetic reconnection*

In collisional systems, plasma entropy is produced during reconnection via heating and mixing. Recently, we have identified a thermodynamic phase transition in fully kinetic PIC simulations of magnetic reconnection, corresponding to the transition from resistive to Hall-like reconnection regimes [Jara-Almonte and Ji, PRL, 2021]. Here, we extend this analysis to examine the entropy production and transport during the onset of kinetic reconnection. It is shown that viscous-like heating is the dominant source of entropy production. In fully collisionless systems, entropy is conserved and only entropy transport is present. In PIC simulations of low-β, force-free reconnection, it will be shown that the local distribution function is well-described by anisotropic κ-distributions, and that the local κ-index can be determined from the local entropy density. Fluid modeling of non-equilibrium entropy transport thus offers one possibility for reduced modeling of particle acceleration processes. Initial results comparing fluid simulations including non-equilibrium entropy transport with fully kinetic PIC simulations will be presented and discussed.