Re-emit experiments in NIF-scale vacuum hohlraums for foot symmetry tuning of indirect drive ignition implosions on the NIF

In indirect drive ignition experiments on the National Ignition Facility (NIF), tuning of the symmetry of the hohlraum radiation drive for the first 2 ns will be assessed by the re-emit technique [1] which measures the instantaneous x-ray drive asymmetry based on soft (800-1200 eV) x-ray imaging of the re-emission of a high-Z sphere surrogate capsule. We performed multi-view re-emit symmetry experiments in 60{\%} scale NIF ignition hohlraums using NIF-like 2 laser cone illumination at 90-110 eV NIF foot radiation temperatures at the Omega facility [2]. We measured radiation symmetry sensitivity to inner/outer beams power balance and we assessed the residual radiation asymmetry of the patched diagnostic holes and missing laser beams required for soft x-ray imaging based on orthogonal polar images. The experimental data accuracy validated that required for NIF. Finally, we will discuss the design of a 90{\%} scale experiment planned for Omega and the implications of all results to our NIF symmetry tuning strategy. [1] N. Delamater, G. Magelssen, A. Hauer, \textit{Phys. Rev. E} \textbf{53}, 5241 (1996). [2] E.L. Dewald, \textit{et. al.,} submitted to Rev. Sci. Instrum.