Line analysis of EUV spectra of molybdenum laser-produced plasmas using a comparison method

• Published in: Journal of quantitative spectroscopy & radiative transfer Vol. 265; p. 107565
• Main Authors: Shevelko, A.P., Andreev, S.N., Tolstikhina, Inga Yu
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2021
• Subjects: Comparison method; EUV and X-ray spectroscopy; Highly-charged ions of heavy elements; Plasma diagnostics; Highly-charged ions of heavy elements; Plasma diagnostics; EUV and X-ray spectroscopy; Comparison method
• ISSN: 0022-4073; 1879-1352
• DOI: 10.1016/j.jqsrt.2021.107565

•A comparison of the spectra under study with the spectra of well-diagnosed nanosecond laser-produced plasmas can be used for evaluating the electron temperature in the plasma of heavy elements.•The electron temperature of molybdenum plasma can be obtained from the relative intensities of spectral peaks.•Dielectronic recombination processes play an important role in the formation of the spectral structure. A comparison method for estimating the electron temperature in the plasmas of heavy elements was further developed. The method is based on the diagnostics of laser-produced plasmas from the spectra of light [H]- and [He]-like ions, for which the methods of measuring the electron temperature are well developed and widely used. The spectra of heavy elements are obtained at the same laser intensities on the target as for light elements, which makes it possible to assign a certain electron temperature to each spectrum. The temperature-calibrated spectra of the laser-produced plasmas can be used to estimate the electron temperature of the investigated radiation source (Z-pinch plasmas, tokamak plasmas). The best coincidence of the shape and the structure of the investigated spectrum with the calibrated one determines the electron temperature of the radiation source under study. In this work, the method was applied to diagnose laser-produced Mo plasmas. The electron temperature of the Mo plasmas was determined using the spectra of [He]-like Mg ions. A detailed analysis of the experimental EUV spectra of the Mo plasmas was carried out, which included the identification of the lines of multiply charged Mo11+ - Mo19+ ions, the determination of the spectral features and the contributions of different processes to the spectral structure, and the study of the dependence of the structure on the electron temperature. Theoretical modeling of the EUV spectra of Mo11+ - Mo19+ confirmed the experimental estimates of the electron temperatures. Calculations were carried out for electron temperatures in the range 150–250 eV in order to determine the temperature at which the relative intensities of the spectral peaks in the spectral region λ = 20–180 Å coincide with the experimental ones. The theoretical analysis revealed the important role of dielectronic recombination processes in the formation of the spectral structure at various electron temperatures.