Two-dimensional capsule-hohlraum designs for the National Ignition Facility

This article describes 250, 280, and 350 eV drive temperature copper-doped Be [Be(Cu)] two-dimensional (2-D) capsule-hohlraum designs for the National Ignition Facility (NIF) [Paisner et al., Laser Focus World 30, 75 (1994)]. These capsule-hohlraum designs are a follow-on to the previous one-dimensional capsule designs of Bradley and Wilson [Phys. Plasmas 6, 4293 (1999)]. It is shown that a 2-D 350 eV capsule-hohlraum design scaled from the successful 330 eV design does not ignite, mostly due to poor symmetry. In addition, the 350 eV capsule hohlraum design requires the full 500 TW of the NIF design and 1.66 MJ of the maximum 1.8 MJ designed energy output. It is possible to design a capsule-hohlraum combination that achieves ignition and burn with peak radiation temperatures of 250, 280, and 330 eV. These designs use from 1.3 to 1.6 MJ of laser energy and the successful designs have yields of 16–20 MJ. Changes in symmetry and yield due to changing the focal point of the inner and outer laser cones were examined. The 280 eV capsule can tolerate pointing changes of 40–100 μm before the yield drops by 50%, while even a 40 μm pointing change for the 250 eV capsule causes the yield to drop by a factor of 2 to 100.