Study on the Cross Electrode Type Plasma Generator

This report described the characteristics of the cross electrode type plasma jet genrator, which has been consisted of the cross electrode to lay in the nozzle constrictor and of center electorode. Experiments were made at the arc current range from 20 to 60A for straight polarity jet and 10 to 30 A for reverse polarity jet in Argon gas flow rate from 15 to 40 l/min. The results of this experimental investigation were as follws : The arc voltage versus arc current characteristics for straight polarity jet were drooping characteristics, untill the arc current was 40 A, but for over 40 A, it was positive characteristics. On the other hand, for reverse polarity jet, it was always drooping one. As the gas flow rate increased, the arc voltage of both jets was increased. The arc voltage of reverse polarity jet was higher than straight polarity jet. For straight polarity jet, the ratio of the sum of the cross electrode loss and the nozzle loss to the total loss was rang from 70 to 80%, and the ratio of the cross electrode loss to the former was rang from 70 to 84%. But for reverse polarity jet, the cross electrode loss was down fifth value of straight polarity jet. The thermal efficiency of this generator was rang from 65 to 85% as the general plasma jet generator, and increasing the gas flow rate, it was increase. The mean temperature was below 3015°K. The arc mode of straight polarity jet was indicated the quasisteady mode or steady mode, but for reverse polarity jet, it was always indicated the oscillation mode. At the same power input, the plasme flame length of reverse polarity jet was longer than that of straight polarity jet and so the form of reverse polarity jet was more sharp. Increasing the arc current and the gas flow rate, the core section and the outer flame of straight polarity jet was expanded, but the reverse polarity jet, the core section was only expanded.