Using high-energy radiography measurements of the inner shell shape of double shell implosions*

A double shell capsule consists of an outer shell, a medium between the shells and a high-Z inner shell filled with DT fuel. Double shell targets rely on effectively transferring the kinetic energy of the outer shell to the inner shell to compress the DT fuel. There are many factors that contribute to the shape of the compressed inner shell. Some of these factors are target-related and include the gap between the outer shell hemispheres, inner and outer shell thickness variations, and outer and inner shell offsets. We developed a platform utilizing the current abilities of the Advanced Radiographic Capability (ARC) on the National Ignition Facility (NIF) using Chromium as a surrogate inner shell to measure the inner shell shape. We will present experimental measurements of the inner shell shape, discuss the challenges with determining a shape from the x-ray radiographs, and compare the results with as-shot simulations.