PROCEEDINGS ARTICLE | August 26, 2005
Proc. SPIE. 5867, Optical Modeling and Performance Predictions II
KEYWORDS: Optical amplifiers, Data modeling, Computing systems, Diagnostics, Control systems, Beam shaping, National Ignition Facility, Performance modeling, Laser systems engineering, Fusion energy
The National Ignition Facility (NIF), currently under construction at the University of California's Lawrence Livermore National Laboratory (LLNL) is a stadium-sized facility containing a 192-beam, 1.8 Megajoule, 500-Terrawatt, 351-nm laser system together with a 10-meter diameter target chamber with room for nearly 100 experimental diagnostics. NIF is being built by the National Nuclear Security Administration and when completed will be the world's largest laser experimental system, providing a national center to study inertial confinement fusion and the physics of matter at extreme energy densities and pressures. NIF's 192 energetic laser beams will compress fusion targets to conditions where they will ignite and burn, liberating more energy than required to initiate the fusion reaction. The commissioning of the first four beamlines (a quad) was completed in October 2004 -- a two-year period where a wide variety of energetic laser pulses were propagated through the laser system. Success on many of the NIF laser's missions depends on obtaining precisely specified energy waveforms from each of the 192 beams over a wide variety of pulse lengths and temporal shapes. A computational system, the Laser Performance Operations Model (LPOM) has been developed and deployed during NIF commissioning to automate the laser setup process, and accurately predict laser energtics. For each shot on NIF, the LPOM determines the characteristics of the injection laser system required to achieve the desired main laser output, provides parameter checking for equipment protection, determines the required diagnostic setup, and supplies post-shot data analysis and reporting. LPOM was deployed prior to the first main laser shots in NIF, and has since been used to set up every shot in NIF's first quad (four beamlines). Real-time adjustments of the LPOM energetics model allows NIF to routinely deliver energies within 3%, of requested and provide energy balance within the four beamlines to within 2% for shots varying from 0.5 to 26 kJ (1.053 μm) per beamline. The LPOM has been a crucial tool in the commissioning of the first four beamlines (a quad) of NIF.
