Measurements of the smoothing of beam modulations in targets accelerated by 1.05μm and 0.53μm radiation

Spatially modulated laser beams at 1.05 mu m and 0.53 mu m were used to accelerate mylar disc targets. The response of the target was smoothed by the plasma and the degree of modulation observed on the rear of the target, by pulsed X-ray shadowgraphy, was proportional to 1/I lambda 1.5 . Code comparisons show this is due to thermal conduction in the absorption region and smoothing in the coasting phase of the target motion.