EUV Spectra from Laser-Produced Tungsten Plasmas

We observed the EUV emission spectra from laser-produced tungsten plasmas. The spectral structures were compared by optical thickness due to the critical density difference of 1 × 1021 and 4 × 1021 cm－3 with laser wavelengths of 1064 nm and 532 nm, respectively. We found some spectral structure changes, an increase of emission in 1 - 3 nm region under an optically thick condition while a decrease of a peak near 5 nm for unresolved transition array of 4d - 4f transitions. Some 1.3 - 2.5 nm peaks were attributed to charge states higher than W30+. We showed some dependence of the spectral behavior for the EUV emission.