Fluctuation Phenomena in Planar Thermal Plasma Jet by Diode-Rectified AC Arc Discharge*

Planar Thermal Plasma Jet as an innovative thermal plasma source has been successfully developed on the basis of AC arc with diode-rectification technique. The purpose of the present work is to investigate fluctuation phenomena in this innovative system. Second purpose is to investigate feasibility of this system in surface treatment applications. Arc discharge was generated among 10 electrodes, which were placed in a line. These electrodes were configurated by 4 AC electrodes, 4 diode-rectified electrodes, a cathode, and an anode. Plasma jet fluctuation was successfully visualized by the high-speed camera system at framerate of 10,000fps. Two synchronized high-speed camera observations with arc voltage and current measurement revealed the periodical plasma jet fluctuation. Correlation between the arc fluctuation and plasma jet fluctuation was studied. Obtained results suggest that the planar thermal plasma jet in diode-rectified AC torch expands the possibility of thermal plasma utilization in industrial field.