Arc Temperature Fluctuation near Electrode of Diode-Rectified Multiphase AC Arc

Diode-rectified multiphase AC Arc (DRMPA) has been developed to solve the electrode erosion of conventional multiphase AC Arc (MPA). Temperature fluctuation near the electrode in MPA or DRMPA has not been clarified due to its measurement difficulty owing to strong continuum emissions, while the understanding its fluctuation is crucial to understand electrode phenomena. In the present work, a high-speed camera system with band-pass filters (BPF) was successfully established to visualize fluctuated arc temperature field near electrode with consideration of both line emissions and continuum emissions. Preliminary measurements of optical emission spectroscopy and theoretical calculation of emission coefficients from the argon arc were performed to select the suitable BPFs carefully. The BPFs of 440 ± 5 nm and 480 ± 5 nm were finally selected as most suitable BPF combination for argon arc near the electrode. The obtained experimental results indicated that the arc temperature near the electrodes fluctuated in the range from 15,000 K to 20,000 K. The arc temperature fluctuation in the conventional MPA is more significant than that in DRMPA due to stronger arc swinging motion in MPA. DRMPA is expected to be applied to various material process due to the higher arc temperature and larger high-temperature area than the MPA. Obtained remarks can serve as a reference for the mechanism of electrode erosion and the industrial application of DRMPA.