Shape analysis of DT-filled double shell implosions at the National Ignition Facility

Double shell implosions utilize dense metal shells to compress deuterium-tritium (DT) fuel to fusion conditions. The goal of LANL’s double shell campaign is to achieve a volumetric burn as radiation losses from the DT fuel are trapped by the opaque high-Z shell. The overall performance of double shell implosions relies on efficient collisional transfer of kinetic energy between shells, which requires approximate spherical symmetry of the shells during the implosion. Asymmetries may be seeded by hohlraum radiation drive as well as double-shell-specific capsule fabrication artifacts, such as the outer shell assembly joint or shell offsets.

The LANL double shell team has recently completed several DT-filled double shell implosions which included Mo or W inner shells. Some of these shots included collection of x-ray radiography data which can be analyzed for symmetry. This work will discuss shape analysis results for DT-filled double shells with Mo and W inner shells as well as comparisons between the two and comparisons between experimental results and simulations. Correlations between symmetry in x-ray radiographs and yields, neutron image symmetry, and major metrology features will also be discussed.