Optimization of the Doped Ablator Layers for the Plastic Ignition Capsule

The paper investigates theoretically the optimization of the doped ablator layers for the plastic ignition capsule. The high-resolved one-dimensional implosion simulations show that the inner pure CFI layer of the Si-doped design is excessively preheated by the hard x-ray, leading to the unstable ablator-fuel interface compared to the Ge-doped capsule. This is because that the Si K-shell absorption edge （1.8 keV） is higher than the Ge L-edge （1.3 keV）, and Si dopant makes more hard x-ray penetrate through the doped ablator layers to preheat the inner pure CH layer. So an optimization of the doped ablator layers （called ＂Si/Ge capsule＂） is performed： an Si-doped CH layer is placed next to the outer pure CH layer to keep the high implosion velocity; next to the Si-doped layer is a thin Ge-doped layer, in order to absorb the hard x-ray and protect the inner undoped CH-layer from excessively preheating. The simulations show that the Si/Ge capsule can effectively improve hydrodynamic stability at the ablator-fuel interface while keeping the high implosion velocity.