Effect of pulse current for fluctuating anode attachment

Summary form only given: The anode attachment of the arc plays an important role for the anode erosion characteristics and the anode lifetime. These phenomena are required to prevent the anode erosion. The interaction of the anode attachment with lateral gas forming a cold boundary layer has been researched, previously. The anode attachment stability is applied to the non-transferred torches such as plasma spray, and the quality of the coating depends on these phenomena. However, the reason of anode phenomena has not been elucidate detail. One of the reason of these phenomena is considered to be the ripple of power supply. In this paper, the motion of the anode attachment was taken by using the high speed video camera in order to elucidate the effect of pulse current for fluctuating anode attachment. The plasma gas was argon, and the lateral gases were argon and nitrogen. The arc current is that the base and peak current is to be 20 and 100 A, respectively. The duty ratio is to be 0-100%. The plasma gas flow rate was to be 3 slm of argon, and the lateral gas flow rate was to be 0 to 50 slm, with argon or nitrogen the gases. The exposure time of high speed video camera is 10,000 fps. The fluctuating attachment was occurred by the base and peak current and duty ratio.