Quantitative performance improvement using beam shaping plasma modulation for uranium detection in di-uranate using laser-induced breakdown spectroscopy

Abstract

Di-uranate is the most important uranium hydrometallurgical product in uranium mining and metallurgy. It is an important raw material in the nuclear industry. Rapid and accurate determination of its uranium content is of great significance for product trading and production process control. At present, it mainly relies on traditional methods, namely ferrous sulfate reduction/potassium dichromate oxidation titration, which involves a complex operation process and lengthy analysis time. Laser induced breakdown spectroscopy (LIBS) is a spectroscopic technique based on atomic emission, which has been proven to be very effective in rapid detection of other elements. However, there are still problems such as severe spectral interference and poor quantitative results of the uranium element. This work explored the feasibility of beam shaping modulation technology in improving the spectral interference level of di-uranate samples, and compared the quantitative performance of uranium between the Gaussian beam and flat-top beam. It was found that, compared to the Gaussian beam, the signal intensity of the flat-top beam has been enhanced, and the degree of spectral interference, signal uncertainty, and quantitative performance have also been improved. The signal strength has increased by 1–2 times, and the signal uncertainty has decreased by about 30%. Spectral peaks with severe overlap can be clearly identified, such as Fe I 480.77 nm and U I 481.09 nm. The determination coefficient (R²), root mean square error (RMSE), and relative standard deviation (RSD) of the quantitative model have been improved from 0.9787, 1.4027, and 1.88% of the Gaussian beam to 0.9857, 0.4828, and 1.48% of the flat-top beam. Besides, by calculating the plasma parameters, it was also found that the difference in plasma parameters between samples of the flat-top beam also decreases, which may be an important reason why beam shaping technology can improve quantitative performance. The results based on flat-top beam LIBS provide a basis for online measurement of uranium in di-uranate samples.