Vacuum degree detection performance improvement of vacuum switches based on NELIBS

Abstract

The measurement of vacuum degree and electrification in vacuum switches has been a critical issue constraining the development of vacuum switches for over half a century, remaining unresolved. In recent years, our team has proposed the use of laser-induced breakdown spectroscopy (LIBS) for the non-contact measurement of vacuum switch pressure. However, its application is hindered by relatively high detection limits, low sensitivity, and susceptibility to background noise interference, which result in suboptimal precision. Extensive research has indicated that metal nanoparticles can effectively enhance signal detection capabilities, however, their enhancement effects under low-pressure conditions remain unclear. This study aimed to investigate the enhancement effects of silver nanoparticles (AgNPs) on signals under low-pressure conditions. By analyzing spectral data, plasma images, and radiation integral intensity, we seek to improve the accuracy of vacuum level measurements in vacuum switches. Results showed that in low-pressure environments, AgNPs enhanced spectral signals by up to 7.17-fold, increasing vacuum detection accuracy from 95.7% to 98.05% and extending the detection range by an order of magnitude to 10⁻³ Pa. This enhancement was regulated by particle size and concentration, with 10 nm AgNPs exhibiting better enhancement effects than 5 nm particles. The optimal concentration varied with both particle size and pressure. Nanoparticle-enhanced LIBS (NELIBS) increased the drop in plasma radiation integral intensity, prolonging the pre-expansion state of the plasma when excited and improving the accuracy of vacuum level measurements. This explores the potential of applying nanomaterials to conduct electrical detection in vacuum conditions and lays a theoretical and experimental foundation for optimizing spectroscopic analysis technologies.