Hydrodynamic Instability Growth Measurements at the Ablator-Fuel Interface in Layered ICF Capsule Implosions*

Based on the well-established Hydro-growth Radiography (HGR) concept [1-3] we have successfully developed and fielded a new target platform to measure instability growth at the ablator-fuel interface in layered capsule implosions on the NIF. We present the results of a proof-of-principle experiment for which mode 60 perturbations with an amplitude of 4.4 $\mu$m peak-to-valley were laser-machined at the inside of a 0.8-scale plastic ablator capsule. A 55 $\mu$m thick, polycrystalline DT ice layer was grown on top of these perturbations. High quality radiography data were recorded at 4 times, showing the growth of these perturbations in both the linear and non-linear stage. We find good agreement with preliminary HYDRA simulations that include small-scale perturbations introduced by the laser machining. Future directions will be discussed. \\[4pt] [1] V.A. Smalyuk et al., Phys. Rev. Lett. \textbf{112}, 185003 (2014).\\[0pt] [2] D.T. Casey et al., Phys. Rev. E \textbf{90}, 011102 (2014).\\[0pt] [3] K.S. Raman et al., Phys. Plasmas \textbf{21}, 072710 (2014).