Laser Diagnostics for Elucidation of Vacuum Arc Behavior

Abstract

For applying vacuum circuit breakers (VCBs) to higher voltage class, understanding of the dielectric recovery phenomenon after high current interruption is a key issue. There are various parameters that require measured information, but in particular, the density of electrons and gases, the temperature of electrodes and plasma, the motion of metallic microparticles generated in interruption operation, etc. are particularly demanded. In this article, the electron/metal vapour density measuring method utilizing Shack-Hartmann type laser wavefront sensor, and the recent topics on microparticle-motion measurement are introduced. Shack-Hartmann type laser wavefront sensor has advantage in visualizing two-dimensional electron/metal vapour density distributions without spatial reproducibility, and have been successfully applied to vacuum arc measurement with various kind of electrode. In addition, recent investigation on the motion of microparticle in vacuum gap and the particle-triggered breakdown phenomena are also introduced.