Detection of hydrogen isotopes in Zircaloy-4 via femtosecond LIBS

The analysis of hydrogen isotopes (H-1, H-2, and H-3) is crucial to several applications, including nuclear forensics and safeguards, characterization of nuclear fission and fusion reactor materials, geochemistry, and space exploration. Laser-induced breakdown spectroscopy (LIBS) is a promising tool for the real-time analysis of hydrogen isotopes. However, the accurate, quantitative analysis via LIBS can be challenging due to H-1 contamination on sample surfaces, residual H-1 in the analysis environment, minor amounts of solute H-1, and spectral line broadening. Here, we characterize femtosecond laser induced plasmas from Zircaloy-4 targets with varying H-1 and H-2 concentrations in a He gas environment via spatially and temporally resolved optical emission spectroscopy. The impact of varying ambient gas pressure, the spatial distribution, and temporal histories of species viz., H-1(alpha), H-2(alpha), and Zr I on Zircaloy-4 plasma spectral features are reported. H-1(alpha) and Zr I emission features are found to have different ambient pressure dependencies and are separated in both space and time in the laser induced plasmas. Lastly, the measured H-2(alpha) emission intensities via femtosecond LIBS for a wide range of H-2 concentrations in Zircaloy-4 samples showed a linear trend when plotted versus known H-2 concentration.

Automated summary

This study characterizes the spectral features of femtosecond laser-induced plasmas from Zircaloy-4 targets with varying H-1 and H-2 concentrations in a helium gas environment, revealing different ambient pressure dependencies for H-1(alpha) and Zr I emission features, as well as spatial and temporal separation in the laser-induced plasmas. Furthermore, the measured H-2(alpha) emission intensities via femtosecond LIBS for different H-2 concentrations in Zircaloy-4 samples showed a linear trend when plotted against known H-2 concentrations.