Abstract
Long DC arc plasma was generated in the distance of 400 mm with argon under the atmospheric pressure. It has some typical features of larger thermal plasma volume providing long processing time. High speed video and digital oscilloscope were used to capture the arc column fluctuation and with simultaneous measurement of the arc voltage for analyzing arc column characteristics. Arc column radiation intensity was increased with an increase of gas flow rate in spite of the decrease of the arc column voltage. The interesting phenomenon of the arc voltage decreased according to gas flow rate in the argon arc plasma that was occurred by the thermal pinch. It is very important for industrial application that the arc column core temperature keeping constant between electrodes.
