Shock Timing and Yield Sensitivity Studies for NIF Ignition Capsules

A cryogenic, {beta}-layered NIF ignition capsule with a beryllium ablator that employs a BeO dopant (2% O) for opacity control is described. The design has an optimized yield of 12 MJ and uses a reduced drive hohlraum temperature pulse shape that peaks at {approx} 250 eV. Shock timing sensitivity calculations have been performed for this capsule design. Individual uncertainties of: (1) {approx}200 ps in the timing of the foot pulse; (2) {approx}5% in the x-ray flux of the foot pulse and first step; (3) {approx}10% in the ablator EOS; or (4) {approx} 5 {micro}m in the DT ice layer thickness each have a significant impact on thermonuclear yield. Combined uncertainties have greater impact than isolated, individual issues. For example, a combination of uncertainties of 200 ps in the foot + 2 eV in the foot + 5 {micro}m in the DT thickness results in a calculation that produces only {approx} 1% of the original design yield. A second, more speculative, capsule concept utilizing a liquid DT ablator is also discussed. This design produces a 5 MJ yield in a 250 eV peak drive calculation.