Argon fluoride laser system for high gain direct drive fusion

Design considerations are laid out for 30-60kJ argon fluoride (ArF) amplifier chains suitable for direct-drive laser fusion. An angular multiplexing architecture is explored in detail, from the front-end generation of quasi-coherent pulse trains via dissociation of Ar₂F*, to the level of on-target pre-pulse from diffuse amplified spontaneous emission. Emphasis is laid on achieving high laser efficiency in the 10THz bandwidth needed to suppress cross-beam energy transfer in the target plasma. The ArF laser is well-suited to both conventional and shock ignition approaches in that smooth arbitrary pulse shapes can be generated for the former, and sub-nanosecond shock pulses can be generated for the latter in the same amplifier chain, with controllable pre-pulse at the target. Wall-plug system efficiency is expected to be about 10%.