Spectroscopic Observations of Ablator Mass Mixed into the Hot Spot of NIF Implosions

Megajoule-class hohlraums at the National Ignition Facility (NIF) were used to implode gas-filled (helium/deuterium) plastic shell inertial confinement fusion targets with a buried Ge-doped shell layer offset from the inner gas--shell interface. Hydrodynamic instabilities and jets seeded by isolated shell-surface mass modulations and the gas-fill tube are predicted to mix ablator mass with the hot spot.\footnote{B. A. Hammel et al., \textit{High Energy Density Physics} \textbf{6}, 171-178 (2010).} The measured Ge K-shell line emission (10 to 13 keV) is direct evidence that the Ge-doped ablator material mixed into the hot spot. Estimates of the ablator mass mixed into the hot spot are inferred from the measured brightness of the Ge K-shell emission lines. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302.