Kα X-ray emission from femtosecond laser-material interactions

The Kα X-ray emission from femtosecond laser-material interactions has been measured with a dispersionless Kα X-ray spectrometer in front of and behind the Cu foil targets. The conversion efficiency from laser energy to Kα photons was obtained. Laser pulse width was typically 33 fs and intensity was kept within the range of 1017 W/cm2 to 1019 W/cm2 by changing laser energy from 50 mJ to 5 J. The experimental results show that the intensity of the Kα X-ray increases with the laser energy， and the X-ray background behind the target is better than that in front of the target. With a 100 μm-thick foil, the conversion efficiency is 2.2×10-5.