Studying the fill tube interaction in double shell targets for inertial confinement fusion

One barrier to achieving uniform and efficient compression in inertial confinement fusion capsules is the fill tube, which is the mechanism for delivering liquid fuel to the spherical capsule. The Los Alamos double shell campaign uses two concentric shells with the purpose of maximizing the energy transfer from the laser drive to the outer aluminum shell which then collides with the high-Z inner shell, subsequently compressing the fuel inside. The fill tube disrupts the symmetry of the concentric shells and leads to less compression of the fuel and less energy output. This work attempts to isolate and remediate the detrimental effects of the fill tube, the bore hole (a hole drilled in the capsule to insert the fill tube), and glue. Radiation-hydrodynamics simulations predict a larger bore hole will allow more aluminum jetting into the capsule, and conversely, thicker fill tube walls will close off the bore hole and block aluminum jetting from causing asymmetry and mix. The OMEGA 60 laser was used to compress a planar target and investigate the effects of the bore hole, glue, and fill tube using point-projection and area backlighter radiography. We present design calculations of these experiments and compare to experimental results.