High-repetition-rate, hard x-ray radiation from a laser-produced plasma: Photon yield and application considerations

We present an experimental study of hard x rays produced in laser-produced plasmas. The laser used is a 1 kHz system, delivering 0.7 mJ for 25 fs onto a solid target. The x-ray spectrum was measured with calibrated germanium detectors, allowing a very good estimate of the absolute number of photons emitted from the plasma over a wide energy range; from 7 keV to 0.5 MeV. Assuming a bi-Maxwellian electron distribution with temperatures of 4.5 and 63 keV, theoretical calculations support the experimental findings. The imaging characteristics of the x-ray source were investigated experimentally employing image plates and theoretically based on the electron distribution.