High-Speed Visualization of Electrode Erosion in Multi-Phase Alternating Current Arc

A multi-phase AC arc plasma has been applied in the glass melting technology as a promising heat source. The electrode erosion of the multi-phase arc is one of the most important issues to be solved. In the present work, the high-speed camera system with appropriate band-pass filters was applied to visually observe the dynamic behavior of the electrode metal vapor in the arc on millisecond time scale. By using this system, the evaporation of 2%-thoriated tungsten electrode was visually observed at the anodic period in the case of the 12-phase arc, while electrode evaporation is negligible in the 2-phase arc. High-speed observation of the oxygen entrainment in the arc was also carried out. Results indicated the ambient oxygen is entrained into the arc more easily with increasing the number of the phases. As a result, the electrode evaporation becomes more severe with larger number of the phases.