Using a 2-shock 1D platform at NIF to measure the effect of convergence on mix and symmetry

We describe the use of a robust new 1-D like implosion platform at the National Ignition Facility [G. H. Miller et al., Opt. Eng. 43, 2841 (2004)] to study the effect of convergence on mix and shape. Previous experiments suggest that nuclear yields and ion temperature degrade with increased convergence [M. D. Cable et al., Phys. Rev. Lett. 73, 2316 (1994)] due to enhanced perturbation growth and mix, but little has been reported on the distortion of the shape with time. The 2-shock platform was developed [S. F. Khan et al., Phys. Plasmas 23, 042708 (2016)] to maintain a high degree of sphericity during the whole implosion phase and has a thick, uniformly doped (1% Si) plastic CH shell to minimize the effect of mixing due to hydrodynamic feed-through from the outer ablator surface. An inner layer of deuterated plastic (CD) and hydrogen-tritium (DT) gas fill allows for the measurement of DT neutrons produced by the mix between the gas and ablator. DD neutrons provide information about the hot, unmixed CD re...