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The dynamics and energy flow in Au plasmas produced by a 0.35-/xm laser have been studied with layered targets with 6-and 24-beam spherical illumination from the Omega laser, to understand the processes leading to subkiloelectronvolt x-ray emission. A significant enhancement in x-ray conversion at low intensities is observed for the 24-beam irradiations with higher energy, greater uniformity, and larger targets. Results are interpreted by comparison with hydrodynamics-code calculations. The depth of energy penetration and x-ray emission in the plasma appears to be well understood, but some details of the x-ray time signature and spectra are not.

An intensity dependence of the absorption of 10-/u m laser light on C02-laser-fusion targets has been observed. Absorption on gold spheres increases from 25%--30% at 10^^ W/cm^ to 50%-60% at 10^^ W/cm^, with most of the variation occurring above 10^^ W/cm^ Concurrently, hot-electron temperature scales as T^ot ^I^'^^ over the entire range. The absorption variation is interpreted as enhanced resonant absorption. It is su^ested that as intensity is increased, the critical surface in the irradiated region becomes increasingly unstable, thereby permitting greater surface distortion and more favorable coupling conditions for resonant absorption.

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