Mix mitigation by continuous capsule doping in high-performance implosions on the National Ignition Facility

Mixing of high-density carbon (HDC) ablator material with deuterium tritium fuel has long been identified as a yield degradation mechanism in implosion experiments at the National Ignition Facility (NIF). Recent high-resolution simulations suggest that the source for much of this mixing is the opacity discontinuity caused by the thin layer of tungsten dopant added to the inside of the HDC shell to control x-ray pre-heating. To mitigate this mix source, a continuous doping scheme has been proposed where the dopant ramps up in a piece-wise continuous fashion from zero to its peak concentration, flattops, and then ramps smoothly back to zero. High resolution simulations show that this substantially mitigates short-wavelength mixing and could lead to a factor of two yield enhancement for current NIF implosions. This presentation discusses the design and modeling of this continuous dopant profile. The following presentation will detail the first experimental results testing this new dopant profile on NIF.