Initial operation of the mercury laser: a gas-cooled 10-Hz Yb:S-FAP system

We report initial operation of the Mercury laser with seven 4 x 6 cm S-FAP amplifier slabs pumped by four 80 kW diode arrays. The system produced up to 33.5 J single shot, 23.5 J at 5 Hz, and 10 J at 10 Hz for 20 minute runs at 1047 nm. During the initial campaign, more than 2.8 x 104 shots were accumulated on the system. The beam quality of the system was measured to be 2.8 x 6.3 times diffraction limited at 110 W of output, with 96% of the energy in a 5X diffraction limited spot. Static wavefront glass plates were used to correct for the low order distortions in the slabs due to fabrication and thermal loading. Scaling of crystal grown has begun with the first full size slab produced from large diameter growth. Using an energetics optimization code we find the beam aperture is scalable up to 20 x 30 cm and 4.2 kJ.