Detection of hydrogen isotopes in Zircaloy-4 via femtosecond LIBS

Abstract

The analysis of hydrogen isotopes (¹H, ²H, and ³H) 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 ¹H contamination on sample surfaces, residual ¹H in the analysis environment, minor amounts of solute ¹H, and spectral line broadening. Here, we characterize femtosecond laser induced plasmas from Zircaloy-4 targets with varying ¹H and ²H 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., ¹H_α, ²H_α, and Zr I on Zircaloy-4 plasma spectral features are reported. ¹H_α 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 ²H_α emission intensities via femtosecond LIBS for a wide range of ²H concentrations in Zircaloy-4 samples showed a linear trend when plotted versus known ²H concentration.