NIF CAPSULE DESIGN UPDATE

We describe several ignition capsule designs, for use in the National Ignition Facility, We compare these designs for ablator efficiency, ig nition margin, implosion and stability performance, This study include s capsule designs driven by x-ray drive profiles with both 300 eV and 250 eV peak temperatures. All of the 300 eV designs are tuned to implo de the DT fuel in a nearly identical manner. Capsule designs consist o f an ablator material (CH with Br dopant; polyimid; Be with Cu dopant; and B4C) encasing a layer of solid DT. The dopants alter material opa cities sufficiently to 1) shield the DT fuel from preheat. effects; an d 2) develop an ablation front density profile favorable to implosion stability. B4C has sufficient opacity at 300 eV that a dopant is not, necessary. Issues relating to material properties and fabrication are described.