Abstract

Preliminary experiments have been performed using the Lawrence Livermore National Laboratory Nova laser to study the coupling of 0.35-μm light to solid Au targets. Single beams of Nova were frequency tripled to 0.35-μm wavelength producing pulses with energies up to 2 kJ in a 1-ns square pulse. These beams irradiated 2-mm Au disks in spot sizes varying from 250 to 1500 μm for incident intensities in the range from 6 × 10¹³ to 2 × 10¹⁵ W/cm². Energy absorption and coupling mechanisms are studied as a function of incident intensity and angle. Preliminary results Indicate that absorption at 0.35-μm wavelength is >90 % at intensities up to 2 × 10¹⁵ W/cm². X-ray conversion efficiencies vary from >70% at 6 × 10¹³ W/cm² to <40 % above 10¹⁵ W/cm². This dependence is greater than observed at Argus using much less energy and smaller spots.

© 1986 Optical Society of America