Imaging Shape Transfer to a Metal Inner Shell in Double Shell Implosions*

The double shell concept for inertial confinement fusion utilizes a low-Z ablator that delivers energy to a high-Z inner shell via collisional transfer. The inner shell then compresses the fuel quasi-adiabatically leading to volumetric ignition. Asymmetries in the outer shell that arise from either the x-ray drive or engineering features can imprint on the inner shell during the collision, and this ultimately impacts the shape of the fuel region. Radiation hydrodynamics codes predict that deviations from round result in reduced performance, setting an upper limit on the allowable levels of low mode asymmetries. We present designs for surrogate double shells using chromium and molybdenum inner shells with deuterated foam fills. These mid-Z inner shells allow for efficient imaging with high-energy photons produced by the ARC backlighter, and the neutrons produced in the deuterated foam fuel will be used to assess mixing of the inner shell into the fuel without the added complexity of fill tube fabrication. Performance degradation due to low mode shape will be assessed in these surrogate designs, and the feasibility of imaging the inner shell shape will be discussed.