Calculation of Proton Stopping Powers in Warm Dense Matter using the Mean Force Kinetic Theory

The averaging done to move from a kinetic to hydrodynamic description of a plasma can lead to loss of information. One key energy transfer and heating mechanism lost in the averaging is the stopping power. This refers to the drag force and resulting energy transfer experienced by a high energy charged particle as it interacts with a surrounding plasma. This can be especially important for fusion and other high energy density physics experiments where energy balance in the system is important. We present a method based on the Mean Force Kinetic Theory (MFKT) [S. D. Baalrud and J. Daligault, Phys. Plasmas 26, 082106 (2019)], to calculate the free-free contribution to proton stopping powers in a Warm Dense Matter system. The MFKT is based on an expansion about equilibrium instead of about the strength of correlations and extends plasma theory into the strongly coupled regime. In order to extend the MFKT to Warm Dense Matter, degenerate electrons must be treated separately. Their degenerate screening is modeled through the potential of mean force calculated using an Average Atom and Quantum Hyper-Netted Chain model [C. E. Starrett and Saumon, HEDP 10, 35-42 (2014)]. Additionally, collisions involving the degenerate electrons are treated quantum mechanically to calculate the correct scattering cross-sections.