Calculated gamma-ray images from simple models of imploded ICF capsules for inference of structure at stagnation

New gamma-ray images of fusion capsules* at ICF facilities raise the question of how to interpret such data. Comparisons of observed images and calculated images from detailed 2D and 3D rad-hydro capsule simulations will be useful, but it may be expensive to carry out such analyses, and to interpret discrepancies. So, to complement such detailed analyses, we investigate the use of simple static models of the imploded capsule, allowing a rapid scan of model parameter space followed by the inference of best-fit parameters, to describe what the image tells us about the imploded capsule. A typical model might consist of a two-region shell-and-core geometry, parameterized by inner and outer radii of the shell and the regions’ carbon densities. We use the MCNP6® code to calculate the image resulting from 4.4-MeV C(n,n')γ gamma rays, together with the DT fusion gamma rays. We discuss the additional constraints on the models from gamma-ray reaction-history measurements, and the importance of data such as the DT branching ratio and the scintillator response, in computing these images.

*V. Geppert-Kleinrath et al., "Gamma Imaging of Inertial Confinement Fusion Implosions", this conference