Analysis of extreme ultraviolet spectral profiles of laser-produced Cr plasmas*

Radiation from laser-produced plasmas was examined as a potential wavelength calibration source for spectrographs in the extreme ultraviolet (EUV) region. Specifically, the EUV emission of chromium (Cr) plasmas was acquired via spatio-temporally resolved emission spectroscopy. With the aid of Cowan and flexible atomic code (FAC) structure calculations, and a comparative analysis with the simulated spectra, emission peaks in the 6.5–15.0 nm range were identified as 3p–4d, 5d and 3p–4s transition lines from Cr5+–Cr10+ ions. A normalized Boltzmann distribution among the excited states and a steady-state collisional-radiative model were assumed for the spectral simulations, and used to estimate the electron temperature and density in the plasma. The results indicate that several relatively isolated emission lines of highly charged ions would be useful for EUV wavelength calibration.