EUV Emission from a Regenerative Liquid Target Laser-Produced Plasma

We demonstrated the efficient water-window extreme ultraviolet (EUV) source using a regenerative liquid metal target irradiated by a 10-Hz, 150-ps, solid-state laser at a wavelength of 1.064 µm. A regenerative liquid bismuth (Bi) target with a diameter of 30 µm was continuously injected into a vacuum. The number of photons was about 1 × 1013 photons/(sr · shot) in the spectral region from 2.3 to 4.4 nm, which was attributed to be n = 4 – n = 4 (Δn = 0) and n = 4 – n = 5 (Δn = 1) transitions. The fast ion was also observed with a maximum energy of 140 keV from a hot, dense Bi plasma.