Measurement of transient temperature using laser-induced breakdown spectroscopy (LIBS) with the surface temperature effect

Abstract

A method based on LIBS technology for measuring transient surface temperatures with a time resolution of several μs was proposed in this study, which holds great significance for fast sliding friction processes in linear electromagnetic propulsion, gun barrels, and high-speed trains. The effects of surface temperature on laser-induced plasma emission spectra were studied, and it was found that both the spectral intensity and signal-to-noise ratio increased with increasing temperature. The mechanism of the surface temperature effect was revealed by interferometry and spectral analysis techniques, which were mainly related to the processes of plasma ablation and surface air heating. Finally, three algorithms including SPF, PLS, and BP-ANN were used to predict the surface temperature, and the results showed that BP-ANN performed best in the 1 μs, 2 μs, and 3 μs exposure time. Under an exposure time of 3 μs, the regression coefficient (R²) and root mean square error (RMSE) could reach 0.9992 and 2.466, respectively. This research would provide a new measurement technology for transient temperature in high-speed physical processes.