A Case Study of Using X-Ray Thomson Scattering to Diagnose the Plasma Conditions of Laser-Direct-Drive, DT Cryogenic Implosions at Stagnation

The design of inertial confinement fusion ignition targets requires radiation-hydrodynamics simulations with accurate models of the fundamental material properties (i.e., equation of state, opacity, and conductivity). Validation of these models is needed via experimentation. This work presents spatially integrated, spectrally resolved x-ray Thomson scattering as a diagnostic possibility. Previous work focused on currently feasible x-ray sources available on OMEGA to demonstrate this platform's capability of resolving the plasma conditions of the compressed shell at two-thirds convergence. Expanding this work to diagnose peak compression, a different source of x rays is required to overcome the significant self-emission from the imploded target. Here we propose the use of an x-ray free-electron laser (XFEL) source to resolve the plasma conditions induced in the hot spot. Synthetic scattering spectra were generated using 2-D implosion simulations from the LILAC code that were post-processed with the x-ray scattering model that is incorporated within SPECT3D. While an XFEL is not yet available at an ignition-scale laser facility, this work suggests that such a facility would unlock powerful diagnostics capabilities.