Cleanliness for the NIF 1ω Laser Amplifiers

During the years before the National Ignition Facility (NIF) laser system, a set of generally accepted cleaning procedures had been developed for the large 1ω amplifiers of an inertial confinement fusion laser, and up until 1999 similar procedures were planned for NIF. Several parallel sets of test results were obtained from 1992 to 1999 for large amplifiers using these accepted cleaning procedures in the Beamlet physics test bed and in the Amplifier Module Prototype Laboratory (AMPLAB), a four-slab-high prototype large amplifier structure. Both of these showed damage to their slab surfaces that, if projected to operating conditions for NIF, would lead to higher than acceptable slab-refurbishment rates. This paper tracks the search for the smoking gun origin of this damage and describes the solution employed in NIF for avoiding flashlamp-induced aerosol damage to its 1ω amplifier slabs.