A stable 12-phase alternating current (AC) arc has been successfully applied to melt granulated glass materials. The discharge behavior and the high temperature region of the plasma system can be controlled by the electrode configurations. In this study, the temporal characteristics of the arc discharge were examined by image analysis with a high-speed camera. The instabilities of particle surface temperature were investigated by a high-speed camera equipped with a band-pass filter system. This is the first time that particle temperature measurement of millisecond order has been performed by high-speed camera. Results show the amplitude of the variation in the in-flight particle temperature depends on the amplitude of the arc fluctuation. The periodicity of arc fluctuation is strongly related with transition of discharge pattern.