AbstractHigh repetition (320 pps), high average power (100 W) pulse Nd:YAG slab laser has been developed for x-ray driver. A strong X-ray emission around 10.8 nm, which wavelength is attractive for x-ray projection lithography, was generated from cryogenic Xe targets pumped by this laser pulses. CO2 and H2O were also tested for cryogenic targets and we found that the emission intensity from Xe around this wavelength region was at least 10 times higher than that from H2O, CO2.