ABSTRACT
Precise assessment of the high fluence performance of pulse compressor gratings is necessary to determine the safe operational limits of short-pulse high energy lasers. We have measured the picosecond laser damage behavior of multilayer dielectric (MLD) diffraction gratings used in the compression of chirped pulses on the Advanced Radiographic Capability (ARC) kilojoule petawatt laser system at the Lawrence Livermore National Laboratory (LLNL). We present optical damage density measurements of MLD gratings using the raster scan method in order to estimate operational performance. We also report results of R-on-1 tests performed with varying pulse duration (1-30 ps) in air, and clean vacuum. Measurements were also performed in vacuum with controlled exposure to organic contamination to simulate the grating use environment. Results show sparse defects with lower damage resistance which were not detected by small-area damage test methods.
ABSTRACT
We have found the local temporal shot-to-shot variation of the NIF high-energy laser system to be relatively constant (~3.4% to 4.2% of the mean fluence). We have developed a statistical model that predicts the maximum fluence distribution any particular location will be exposed to after N independent shots (the so-called max-of-N fluence distribution) using the measured shot-to-shot variance; this method allows for an estimate of maximum optics fluence exposure.
