Impact of High-Z materials on Inertial Confinement Fusion performance: X-ray spectroscopy

Mixing of high atomic number (high-Z) materials from the capsule shell into the fuel core is one of the main degradation mechanisms in inertial confinement fusion (ICF) performance. These high-Z impurities perturb the fuel via radiation cooling, reducing temperature and fusion yield. While the mixing dynamics are widely studied, the impact of the impurities on the core is typically assumed to be accurately captured by the physics models. Prior work challenges this assumption by introducing controlled amounts of Ar, Kr, and Xe directly into the fuel, isolating their effects from mixing dynamics¹. However, previous models failed to capture the observed sensitivity of implosion performance to high-Z pre-mix concentration.

Here, we revisit these experiments to benchmark xRAGE², an Eulerian radiation-hydrodynamics code developed at LANL. Beyond historical yield and burn data, we analyze X-ray spectra to extract electron temperature, density, and their dependence to impurity concentration. These are interpreted using the ABAKO³ collisional-radiative model to simulate atomic kinetics and spectral emission. In addition, new experiments have been designed to isolate and evaluate the atomic physics built in xRAGE.



¹Dodd et al., PoP 19, 042703 (2012)

²Haines et al., PoP 29, 083901 (2022)

³Florido et al., PRE 80, 056402 (2009)