Enhancement by Spark Discharge in LIBS Detection of Copper Particle Contamination in Oil-Immersed Transformer

The detection of copper particles in transformer oil based on laser-induced breakdown spectroscopy (LIBS) technology has been preliminarily studied, but its limit of detection (LOD) needs to be further strengthened. Therefore, spark-discharge assistant method was used to solve the problem, and its enhancement mechanism has been studied in the research. The study of the correlation between spark-discharge-assisted LIBS (SD-LIBS) spectral intensity and Cu concentration shows that spark discharge has a significant increase in plasma size and spectral intensity; for Cu atomic lines at 324.75 and 327.39 nm, the determination coefficient ${R}^{{2}}$ between their internal standard correction intensity and Cu concentration is promoted to 0.996 and 0.997, respectively; spark-discharge assistant method improves the LOD of LIBS from 0.775 to 0.112 $\mu \text{g}$ /g. Due to the great improvement in detection performance, the application prospect of LIBS as fine particles detection method in transformer oil has become practical.