Increasing robustness of indirect drive capsule designs against short wavelength hydrodynamic instabilities

Targets meant to achieve ignition on the National Ignition Facility (NIF) [J. A. Paisner, J. D. Boyes, S. A. Kumpan, W. H. Lowdermilk, and M. S. Sorem, Laser Focus World 30, 75 (1994)] have been redesigned and their performance simulated. Simulations indicate dramatically reduced growth of short wavelength hydrodynamic instabilities, resulting from two changes in the designs. First, better optimization results from systematic mapping of the ignition target performance over the parameter space of ablator and fuel thickness combinations, using techniques developed by one of us (Herrmann). After the space is mapped with one-dimensional simulations, exploration of it with two-dimensional simulations quantifies the dependence of instability growth on target dimensions. Low modes and high modes grow differently for different designs, allowing a trade-off of the two regimes of growth. Significant improvement in high-mode stability can be achieved, relative to previous designs, with only insignificant increase in...