National Ignition Facility Installs Its 1000th Optical Element Unit

LIVERMORE, Calif., Nov. 23 -— The staff at the National Ignition Facility (NIF), the world's largest laser project, has surpassed an ambitious goal set a year ago -- to install 1000 line-replaceable units (LRUs) by the end of October 2005. The workers accomplished the goal with a couple of weeks to spare.

The LRUs are the complex modules containing optics and instrumentation, through which laser beams must pass as they make their way through the enclosed beamline to a tiny gas-filled pellet in the target chamber.

The National Ignition Facility’s 1000th line-replacable optical unit is maneuvered into position. (Photo: Lawrence Livermore National Laboratory)

When assembled, NIF LRUs are precision electro-optical/mechanical structures weighing between 500 and 1000 kg. The completed facility will have about 5760 LRUs. LRU components are assembled and tested in a cleanroom environment to validate the cleanliness, alignment and operation of these complex assemblies before large robotic forklifts gently insert the LRUs into the beamlines from below.

The NIF is a facility of the Lawrence Livermore National Laboratory. When complete, it will contain a 192-beam, 1.8-MJ, 700-TW laser system adjoining a 10-meter-diameter target chamber with room for nearly 100 experimental diagnostics. NIF’s beams will compress and heat small capsules containing a mixture of hydrogen isotopes of deuterium and tritium. These fusion targets will ignite and burn, liberating more energy than is required to initiate the fusion reactions. NIF experiments will allow scientists to study physical processes at temperatures approaching 100 million K and 100 billion times atmospheric pressure. These conditions exist naturally only in the interior of stars and in nuclear weapon detonations.

Eight of NIF's 192 beams have now been commissioned and placed into service. They have already achieved an energy output of 153 kJ, which exceeds the milestone requirement of 125 kJ. The entire NIF project is expected to be completed in mid-2009, with ignition experiments beginning a year later.

For more information, visit: www.llnl.gov