TARGET ALIGNMENT IN THE NATIONAL-IGNITION-FACILITY

Accurate placement of hundreds of focused laser beams on target is nec essary to achieve success in the National Ignition Facility (NIF). The current system requirement is less than or equal to 7 mu rad error in output pointing and less than or equal to 1 mm error in focusing. To accommodate several system shots per day, a target alignment system mu st be able to align the target to chamber center, inject an alignment beam to represent each shot beam, and point and focus the alignment be ams onto the target in about one hour. At Lawrence Livermore National Laboratory, we have developed a target alignment concept and built a p rototype to validate the approach. The concept comprises three systems : the chamber center reference, target alignment sensor, and target al ignment beams.