Large-scale Implosions Using HDC Ablators for the Frustraum

A diamond-shaped hohlraum (“frustraum”) proposed by Amendt† may provide adequate radiation symmetry for large capsules (1500 m radius) and T_radin the range 290-300 eV while only requiring < 1.8 MJ of laser energy. The implosion physics and designs for these large capsules are presented here and compared to nominal scale (1100 m radius) HDC implosions. The fuel adiabat for the large-scale capsules ranges from 2.5 to 4.5. Larger scale has higher 1D margin or GLC, e.g., the adiabat 4 design gives a 2D yield of 20 MJ while the nominal-scale adiabat 4 design has a 2D yield of only about 0.5 MJ. Lower hard x-ray fraction (14%) from the frustraum with a DU wall results in neutral Atwood number at peak velocity. This reduces mix and gives a high clean fuel fraction of 95%. Large-scale capsules are also robust to fuel preheat, hotspot contamination, and tent and fill-tube perturbations. The methods used for the large-scale designs are the same for the postshot modeling of N170601, which give close agreement with the data. †Amendtet al., this conference.