A Kinetic Theory Perspective of Energy Conversion in Weakly Collisional Plasmas

M. Hasan Barbhuiya, Ph.D.

Energy conversion and evolution in weakly collisional plasmas is challenging since collisions are too infrequent to evolve the system to a state of local thermodynamic equilibrium. This results in phase space densities that can have complicated shapes and are not Maxwellian. Such structured phase space densities encode rich information about plasma energization that the fluid perspective of energy evolution/conversion cannot capture. In this talk, a kinetic theory perspective on energy evolution will be presented, focusing on how phase-space structures contribute to changes in electromagnetic, bulk flow, and internal energies. Using a new phase space diagnostic technique called the kinetic pressure–strain, that complements existing technique of field-particle correlation, how different particle populations contribute to energy evolution at phase space will be quantified. By employing high-resolution fully kinetic simulations of magnetic reconnection, we will link the phase space and fluid pictures of energy evolution, thus highlighting the dominant electron populations contributing to Ohmic heating and pressure-strain interaction channels. We will also discover that the dominant populations contributing to Ohmic heating and pressure–strain interaction need not be the same near the electron diffusion region, underscoring the importance of a phase-space–resolved view of plasma energization. Insights from this study can guide our interpretation of in situ observations of multi-population non-Maxwellian phase space densities and associated energy evolution, ultimately advancing our understanding of energy evolution/conversion in weakly collisional plasmas found throughout the heliosphere.

To participate in this event virtually via Zoom, go to https://uiowa.zoom.us/j/95662833839?from=addon.