Output energy and conversion efficiency of extreme ultraviolet radiation from rare gas cryogenic targets

摘要

Characteristics of extreme ultraviolet (EUV) light at the wavelength between 5 to 20 nm from rare gas cryogenic targets irradiated with a nano-second laser pulse are studied. Spatial distribution of the EUV light and the ion current was measured and found to vary as cos~2θ and cos~6θ, respectively, where θ is an angle to the target normal. Energetic ions were detected, which had a velocity of the order of 106 cm/s. According to the observed cos~2θ spatial distribution, the spatially-integrated total EUV output energy for the xenon cryogenic target was evaluated to be 1.5 mJ/pulse, leading to the conversion efficiency of 0.2%/pulse.