First early time symmetry tuning experiments for indirect drive ignition implosions on the National Ignition Facility

In ignition experiments on the National Ignition Facility (NIF), the symmetry of the hohlraum radiation drive for the first 2 ns is tuned using the re-emit technique [1]. To achieve this, the capsule is replaced by a high-Z ``reemit'' sphere so that the incident drive symmetry can be inferred by soft x-ray imaging of the sphere re-emission pattern [2]. We report on the first re-emit symmetry experiments performed on NIF in full ignition scale hohlraums that achieved 1{\%} low mode accuracy. We will discuss results demonstrating the sensitivity of the radiation symmetry incident on the capsule to inner-to-outer laser beams wavelength shift that influences the inter-cone energy transfer, as well as to inner/outer beams power fraction that is used to tune the P2/P0 Legendre polynomial of the radiation flux at the capsule. \\[4pt] [1] E.L. Dewald, \textit{et. al.,} Rev. Sci. Instrum. 79, 10E903 (2008).\\[0pt] [2] N. Delamater, G. Magelssen, A. Hauer, \textit{Phys. Rev. E} \textbf{53}, 5241 (1996).