Quantitative analysis of hydrogen isotopes in hydrogen storage material using laser-induced breakdown spectroscopy

Abstract

• The scanning-coaxial LIBS system is set up for in-situ measurements in fusion reactors. • Titanium foil with different hydrogen and deuterium contents is prepared and determined. • Hydrogen isotopes are analyzed quantitatively using the internal standard method (ISM) and the calibration free method (CF-LIBS). • The single sample correction calibration free method (SSCCF) is applied to improve the accuracy. The accurate determination of hydrogen isotopes in materials is always a challenge for laser-induced breakdown spectroscopy (LIBS). In this study, the content of hydrogen isotopes in hydrogen storage materials is quantitatively analyzed by LIBS using the internal standard method (ISM) and the calibration-free method (CF-LIBS), respectively. Based on the self-built LIBS system, the concentrations of hydrogen and deuterium in titanium hydride with various stoichiometric ratios are quantitatively analyzed. The local thermodynamic equilibrium (LTE) conditions of the plasma are evaluated by the calculation results of the plasma temperature and density: the plasma temperatures are 16000 ± 1000 K calculated by Boltzmann diagram of titanium, and the plasma electron densities are about 10 22 m −3 calculated by the H α line of spectra. Through integral intensity correction, the correlation coefficient of the calibration curves of hydrogen and deuterium is successfully increased by 3% in the internal standard method; The single sample correction is used in CF-LIBS to improve the accuracy of the measurement of hydrogen isotopes in titanium hydride, and the calibration results demonstrate that the average absolute errors are 8.3% and 3.2% for hydrogen and deuterium. We also compare the calculated contents of hydrogen isotopes in titanium hydride by integral intensity correction internal standard method (IICIS) and single sample correction calibration-free method (SSCCF). The SSCCF increases the accuracy of the hydrogen isotope contents compared with CF-LIBS in the range of 20 to 55 at.%. The results are not as precise as the IICIS but meet the ITER requirements in a way. The results provide a valuable reference for the precise measurement of hydrogen isotope content in materials for applications in hydrogen energy, nuclear energy, and nuclear technology.