Measurement of KrF-laser–plasma x-ray radiation from targets with various atomic numbers

Measurements of the x-ray conversion efficiency (h{ν}{≥}100 eV) for a KrF-laser--produced plasma are reported. Planar targets with atomic numbers varying from 4 to 82 were irradiated by moderate intensities (<10¹³ W/cm²) of 0.25-{μ}m KrF-laser light and the resulting emission was observed by several detectors sensitive to x-ray photon energies from 100 eV to 15 keV. Most of the radiation appeared as xuv and was measured by x-ray diodes to obtain the conversion efficiency as well as the angular distribution of the emission. The x-ray emission both above and below 1 keV was found to display marked variation with atomic number, as successive atomic shells are ionized. These measurements are supplemented by spatial and temporal observations of the keV x-ray emission which also show variations with target atomic number.