Design of the NIF Cryogenic Target System

The U.S. Department of Energy has embarked on a campaign to conduct credible fusion ignition experiments on the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in 2010. The target assembly specified for this campaign requires the formation of a deuterium-tritium fuel ice layer in a 2-mm-diam capsule at the center of a 9-mm-long × 5-mm-diam cylinder, called a hohlraum. The ice layer must be formed and maintained at temperatures below 20 K. At laser shot time, the target is positioned at the center of the NIF target chamber, aligned to the laser beams, and held stable to <7-m root-mean-square. We have completed the final design of the cryogenic target system and are currently integrating the devices necessary to create, characterize, and position the cryogenic target for ignition experiments.