Optimization of X-Ray-Emission from a Laser-Produced Plasma in a Narrow Wavelength Band

The X-ray emission from laser-produced plasmas at an X-ray wavelength of approximately 10.4 nm was measured for Al and Gd target materials. The laser power density on the target surface was varied between 1.5 x 10(10) and 3 x 10(12) W/cm2 to obtain different electron temperatures. The output from the plasma was measured using an X-ray reflecting Pd-C multilayer coating as a wavelength-selective element and a diamond photoconductive detector. The emission at 10.4 nm is strongest at the low end of the power density range investigated. A strong increase is found for Al targets due to a contribution of line radiation, which is not present in the Gd plasmas. The measured conversion efficiency for Al plasmas was (4.5 +/- 1)% in a 3% bandwidth at an X-ray wavelength of 10.4 nm.