基于 FO-LIBS 技术的真空开关真空度在线检测方法

As a primary switching device in modern power systems, vacuum circuit breakers have become dominant in medium-voltage applications. However, the lack of reliable online vacuum degree monitoring methods limits routine operation and maintenance, as well as the wider adoption of vacuum circuit breakers in higher voltage levels. In this study, a fiber-optic laser-induced breakdown spectroscopy(FO-LIBS) approach is proposed for online vacuum degree detection in vacuum circuit breakers, effectively addressing the issues of limited flexibility and complex field operation inherent in conventional LIBS systems, while enhancing protection for both detection and analysis equipment. By employing fiber optics for laser delivery and coaxial plasma signal collection, a long-focus double-lens refocusing probe with a mirror-to-sample distance of 110 mm was designed to suit the vacuum circuit breaker application scenario. The focused beam has a diameter of 930 μm, featuring lower peak intensity and more uniform energy distribution. The plasma generated under varying vacuum degrees exhibits distinct expansion dynamics that differ from those in conventional open-path LIBS. Through plasma spectral and imaging diagnostics, the influence of ambient pressure on plasma morphology and temporal spectral evolution was investigated. The pressure-response characteristics of four spectral features are analyzed, and these features are further used for inverse estimation of vacuum degree. Furthermore, a random forest-based spectral classification algorithm was developed, achieving an accuracy of 91.3%. The proposed FO-LIBS system also demonstrates excellent flexibility and adaptability under complex operational conditions.