Authors: Paul Cassak (West Virginia University), Hasan Barbhuiya (West Virginia University)

Energy conversion between bulk kinetic and thermal energy in weakly collisional and collisionless plasmas, described by the pressure-strain interaction, has been the subject of intense scrutiny.  Pressure-strain interaction is commonly decomposed into pressure dilatation and Pi-D, isolating energy conversion via compressible and incompressible physics, respectively. Here, we summarize three recent studies. First, we propose an alternative decomposition of pressure-strain interaction into PDU and Pi-D_shear that instead isolates flow convergence and bulk flow shear, respectively. We provide kinetic descriptions of the decompositions and explain the apparent paradox of what is means to have negative Pi-D. Second, for applications to magnetized plasmas, we derive the pressure-strain interaction in a magnetic field-aligned coordinate system. This results in its decomposition into eight terms, each with a different physical mechanism that changes the thermal energy. Third, we use particle-in-cell simulations of 2D reconnection to plot the decompositions in both Cartesian and magnetic field-aligned coordinates thereby identifying the different physical mechanisms for the energy conversion. The results of this study are readily applicable for interpreting numerical and observational data of pressure-strain interaction in plasma processes such as reconnection and turbulence.