Implementation of a Novel Monte Carlo Radiation Transport Code for Modeling Nonthermal Fe Kα Line Generation in a Dense MagLIF Plasma

Measuring the energy distribution (spectrum) of nonthermal radiation is a valuable diagnostic for Z-pinch plasmas. However, the spatial origin and transport of these X-rays are challenging to study in Z-pinches due to broad charge state distributions and spatial gradients of nonthermal emitters. Knowledge of this information can refine our understanding of plasma radiation, enhance the microphysics of multiphysics simulations, and constrain future Z-pinch experiments and diagnostics. In this work, nonthermal iron \text{K}\alpha X-rays are modeled in a Magnetized Liner Inertial Fusion (MagLIF) plasma produced on Sandia National Laboratories' Z-machine using a novel Monte Carlo radiation transport code. The code employs an ancillary screened-hydrogenic atomic data package to self-consistently calculate transport of thermal photons from a fusion core into a beryllium liner shell with 114 ppm iron impurities. Iron fluorescence production in the liner shell is analyzed with spatial statistics, providing novel insight into the origin of nonthermal radiation over a broad region of the plasma shell. Spatial analysis indicates an average radius of fluorescence production that is less than the radial midpoint of the liner plasma, suggesting enhanced photoabsorption near the boundary between the fusion core and liner plasma. Results include an approximated average iron ionization, average bulk thermal electron temperature, and iron K-shell fluorescence yield. A radial temperature profile from deposition of transport photons as well as an emergent transmission spectrum with escaped iron \text{K}\alpha and \text{K}\beta intensities are constructed. Spectroscopic utility of the code is validated against experimental MagLIF data, showing good agreement among spectroscopic features.