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AWE’s Orion Laser facility contains ten nanosecond beamlines, each employing a series of flash-lamp pumped disk amplifiers capable of generating up to 750 J in 1 ns at 1053 nm. Discharge through the flash-lamps, however, causes unwanted disk heating which induces wavefront aberrations. This immediate effect, referred to as ‘prompt aberration’, alters the onshot wavefront compared to the wavefront of the alignment beams. In addition, a thermal load remains on the disks between shots, causing an evolution of both the alignment and on-shot aberrations over a typical day. The combination of the prompt aberrations and wavefront evolution has limited performance. After approximately six shots the alignment aberrations became so severe that further alignment was impossible. Operations would then cease to allow the disks to cool and the wavefronts to return to normal for the start of the following day. This paper reports on the development and implementation of static wavefront correctors. By mitigating the effect of the prompt aberrations, the alignment beam wavefront better matches the on-shot aberrations, and no longer limits operations, allowing more shots to be fired in a day. The wavefront analysis is discussed and shows the prompt aberration to comprise mainly of ~1 μm of defocus and astigmatism, averaged across many shots and all beamlines. Compensating static correctors are shown to reduce the effect of the prompt aberration to ~0.2 μm. The outcome indicates the possibility of firing more shots in a single day’s operation.
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