Increased x-ray conversion efficiency from gold plasmas irradiated with spatially and temporally incoherent light

The efficiency with which 1.05 μm laser light is converted into x rays with energy less than 1.5 keV in high Z materials (gold) is increased by approximately 20% with the use of spatially and temporally incoherent light when compared to a nominal, high-powered laser beam with an identical average irradiance of 1014 W/cm2. This effect is not a result of increased laser light absorption, laser bandwidth, nor reduced hot electron generation for the incoherent light, but is probably due to the change in the short scale length (∼100 μm) laser light intensity distribution in the target plane. The absolute levels of stimulated scattering and hot electron generation were small in all cases. Incoherent illumination reduced stimulated Brillouin scattering levels from 1.1% to 0.2% and, similarly, hot electron generation was decreased from 0.1% to 0.07%