Numerical simulations of high-resolution in-flight density profile measurements on Omega EP*

The in-flight shell-density profile is an important characteristic of an Inertial Confinement Fusion implosion which depends on the shell adiabat and affects shell convergence and peak density. Experiments on OMEGA-EP at the Laboratory for Laser Energetics were performed to measure the density profile of a planar CH foil driven by a single OMEGA EP beam. X-ray radiography imaging used Fresnel Zone Plates to achieve, for the first time, an unprecedented resolution of about 1 mm. Images were obtained at four time moments capturing the first-shock transit through the foil and the foil density profile evolution during acceleration. The measured profiles are compared with simulations using radiation-hydrodynamic code DRACO. Multi-dimensional effects which are consequence of the laser beam being wider than the foil are assessed. Sensitivity of the density profile to the equation of state, thermal and radiation transport, as well as the laser pulse shape is discussed.