\textbf{Visualizing hydrodynamic mix at capsule stagnation using spectroscopic marker layers in ICF implosions on the NIF}*

Hydrodynamic instabilities in ICF implosions can cause ablator material mixing into the hot spot plasma and shell rho-r variations which adversely impact the hot spot assembly and subsequent nuclear performance. To better understand this process in indirectly driven capsule implosions at the NIF, we have added a thin Ge dopant layer at the gas-ablator and ice-ablator interface in a series of non-DT layered symmetry capsule (Symcap) and DT layered implosions. This provides a spectroscopic marker for visualizing hydrodynamic mix during capsule stagnation. Comparison of the high-resolution, spectrally filtered Symcap hot spot images with those from `standard candle' Symcap implosions that do not have a Ge dopant allows us to measure how far ablator material is mixed into the hot spot. Complementary x-ray spectroscopy measurements constrain the thermodynamic state of the mixed ablator material. While the Symcap experiment shows enhanced x-ray emission from both the tent and fill-tube locations, the subsequent Ge- and Si-doped layered DT experiments show enhanced x-ray emission dominated by the fill-tube perturbation.