Hydrodynamic Mixing of Ablator Material into the Compressed Fuel and Hot Spot of Direct-Drive DT Cryogenic Implosions

Hydrodynamic mixing of ablator material into the compressed fuel and hot spot\footnote{S. P. Regan\textit{ et al.}, Phys. Rev. Lett. \textbf{111}, 045001 (2013).\par } of direct-drive DT cryogenic implosions is diagnosed using time-integrated, spatially resolved x{\-}ray spectroscopy. The laser drive ablates most of the 8-$\mu $m-thick CH ablator, which is doped with trace amounts of Ge $\left( {\sim 0.5\mbox{\thinspace at.\thinspace \% }} \right)$ and surrounds the cryogenic DT layer. A small fraction of the ablator material is mixed into the compressed shell and the hot spot by the ablation-front Rayleigh--Taylor hydrodynamic instability seeded by laser imprint, the target mounting stalk, and surface debris. The amount of mix mass inferred from spectroscopic analysis of the Ge K-shell emission will be presented. This material is based upon work supported by the Department Of Energy National Nuclear Security Administration under Award Number DE{\-}NA0001944. Part of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE{\-}AC52{\-}07NA27344.