Authors: M. Hasan Barbhuiya (West Virginia University), Paul Cassak (West Virginia University), James Juno (Princeton Plasma Physics Laboratory), Gregory Howes (University of Iowa), Sarah Conley (Princeton University), Jason TenBarge (Princeton University), Jason Shuster (University of New Hampshire), Subash Adhikari (West Virginia University, University of Delaware)

Kinetic effects in collisionless space plasmas give rise to structured phase space densities that deviate significantly from the local thermodynamic equilibrium (LTE) Maxwellian phase space density. For collisionless plasma phenomena such as reconnection and turbulence, where non-Maxwellianity is observed with satellites and simulations, the pressure-strain interaction and the divergence of the vector heat flux density quantify the changes to the internal energy per particle in the Lagrangian (co-moving) reference frame. However, the aforementioned fluid-type power densities are obtained by integrating moments of the Vlasov equation over velocity-space, thus obscuring the phase space information about the energy conversion due to particles at different velocities. The field-particle correlation (Klein and Howes, Astrophys. J. Lett. 826, L30, 2016) retains the phase space information about the conversion between electromagnetic fields and bulk kinetic energy. Here, we present the analogous terms for the pressure-strain interaction and the divergence of the vector heat flux density that provide information about internal energy changes in phase space. We use this description to analyze electron phase space densities from a symmetric antiparallel reconnection simulation, link the localized phase space regions to changes in internal energy, and tie the phase space description with the fluid description of internal energy evolution.