2005 Volume 23 Issue 2 Pages 270-275
Hollow Cathode Arc (HCA) was developed as a plasma source under the condition of low pressure in the 1960s, and various researches were performed to make clear the mechanism of the HCA. Since the HCA is a plasma source under low pressure environment, it attracts attention as a welding heat source in space. Moreover, the HCA is expected to be useful for the industrial application on the earth, because the melting process by HCA is very active and the penetration is huge in comparison with that by the conventional GTA.
In the previous paper, the discharge and melting process by the HCA has been discussed, and it has been shown that a concentrated columnar arc and a huge penetration are obtained in the case of low gas flowrate.
In the present paper, the current distribution on the anode surface and the floating potential of the HCA column have been made clear and the plasma structure of the HCA has been discussed to understand the heat input to the anode by the HCA. It is concluded that the huge penetration by the HCA in the case of low gas flowrate is closely related to concentrated current distribution on the anode surface and the strong flow of electrons in the HCA.