Detailed analysis of self-absorption profiles of highly-charged tin ions in the EUV region

Abstract

Plasma dynamics simulation is a very effective method for the spectral diagnosis and analysis of plasmas, which has been widely used in the interpretation of spectral structure and evolution analysis of the laser-produced plasmas. In this paper, a simplified radiation hydrodynamic model based on the fluid dynamic equations and the radiative transfer equation, and combined with a steady-state collisional-radiative model was presented and used to analyze the origin of extreme ultraviolet (EUV) spectrum of middle- and high-Z highly charged ions from laser-produced plasma, and has been successfully applied to analyze and simulate the spectrum of laser-produced tin plasma in the EUV spectral region. The results show that there is a good agreement between theoretical simulation and experimental spectrum at a laser power density of 1.90×1011 W/cm2. By comparison of the emission profiles and self-absorption profiles of 4d-4f, 4p-4d and 4d-5p, 5f transition arrays from Sn7+ to Sn11+ ions, the influence of opacity effect to the emission profile was identified. We are succeeded in explaining the origin of self-absorbed band and self-absorbed dips around 13.5 nm in tin spectrum. Our results are expected to provide a reference for the applications of extreme ultraviolet radiation in the fields of lithography, metrology and biological imaging.