Recent progress of the Integration Test Bed

The Integration Test Bed (ITB) is a large-aperture single-beam Nd:glass laser system, built to demonstrate the key technology and performance of the laser drivers. It uses two multipass slab amplifiers. There are four passes through the main amplifier and three passes through the booster amplifier. The output beam size is 360mm by 360mm, at the level of 1% of the top fluence. The designed output energy of ITB at 1053nm is 15kJ in a 5ns flat-in-time (FIT) pulse, the third harmonic conversion efficiency is higher than 70%. The first phase of the ITB has been completed in July 2013. A series of experiments demonstrated that laser performance meets or exceeds original design requirements. It has achieved maximum energies at 1053nm of 19.6kJ at 5ns and 21.5kJ at 10ns. Based on a pair of split third harmonic generation KDP crystals, the third harmonic conversion efficiency of about 70% and 3ω mean fluences as high as 8.4 J/cm 2 have been obtained with 5ns FIT pulse.