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Published on: December 27, 2018
Effect of high humidity environment on the time-resolved spectrum of laser-induced air plasma
Jianyong Cen1, Xin Wang1, Zeguang Li1
1College of Physics and Electronic Engineering, Shanxi Normal University, Taiyuan, 030031, China.
Abstract:
Humidity is an important physical parameter that affects the measurement accuracy of laser-induced breakdown spectroscopy technology. The influence of high humidity on laser-induced air plasma at a microscopic perspective has been investigated by using a high-speed camera and high time-resolved (5 ns) spectrum. The morphological changes of air plasma under high humidity conditions were investigated. The effects of humidity on the spectral line intensity, peak time, lifetime, temperature, and electron density were analyzed. The results showed a positive correlation between the length of laser-induced air plasma and humidity. As humidity increases, the peak intensity and lifetime of the ionic and atomic spectral lines of nitrogen and oxygen decrease, while those of hydrogen atoms line increases. The peak time shows a positive correlation with humidity, indicating that humidity prolongs the time to reach peak intensity across all spectral lines. Humidity exhibits similar effects on both temperature and electron density. High humidity reduces their peak values and delays the time required to reach these peaks. This research can provide valuable experimental insights for the practical application of laser-induced breakdown spectroscopy technology in high humidity environments.
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