Monte Carlo Radiation Transport Simulation of Nonthermal X-Ray Fluorescence in a MagLIF Plasma Produced on Z

Ryan Childers, University of Nevada, Reno

Photo of Ryan Childers

Nonthermal x-rays are a fundamental radiative tool for the investigation of laboratory and astrophysical plasma. For example, K-shell Fe fluorescence lines can reveal plasma conditions when a hard x-ray continuum irradiates a lower temperature plasma near objects like X-ray binaries and active galactic nuclei1. Additionally, nonthermal emission is diagnostically advantageous in laboratory plasma studies due to the energetic production efficiency over a range of atomic Z compared to its thermal counterpart2. In laboratory produced plasmas, nonthermal emission is a signature of non-local energetic processes which reveal non-LTE conditions through radiative transport mechanisms. In the current work, nonthermal fluorescence is simulated in a magnetized liner inertial fusion (MagLIF) plasma using a newly constructed Monte Carlo Radiation Transport code. The code simulates a central Te ~ 4 keV, r ~100 μm thermal core which irradiates the surrounding r ~ 500 μm liner medium composed of Be and 114 ppm Fe. Radiative transport is simulated through atomic photo-absorption, scatter, and decay processes, which are calculated using a newly developed screened-hydrogenic superconfiguration-based atomic code. Atomic characteristics such as average Fe ionization, average electron temperature, and K- and L-shell yields are tracked and calculated. Simulation includes radial temperature distribution fueled by deposition of nonthermal and thermal core photons, spatial distribution of nonthermal Fe Kα and Kβ creation and subsequent transport through medium, and emergent transmission spectrum with escaped Fe Kα and Kβ intensities. Comparison of simulated Fe fluorescence to experimental data is provided.

1J. M. Torrejόn et al., ApJ, 715, 947 (2010)
2D. J. Ampleford et al., SAND2015-10453 (2015)

This research was supported by NNSA under DOE grants DE-NA0003877, DE-NA0003047 and in part by DE-NA0002075. Supported also by NNSA through the Krell Institute Laboratory Residency Graduate Fellowship under DE-NA0003864. Sandia National Labs is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

Abstract Author(s): R. R. Childers1, S. B. Hansen2, A. S. Safronova1, D. J. Ampleford21University of Nevada, Reno - Physics, 89557 USA2Sandia National Laboratories, Albuquerque, NM 87123