A novel experimental method of investigating anode-arc-root behaviors in a DC non-transferred arc plasma torch

A novel experimental method of investigating anode arc root was presented, and a plasma torch with multiple anodes was designed. With this apparatus, the number of anode arc roots, their position, and movement with changes in plasma current and gas-flow rate were studied. Results showed that multiple anode arc roots can coexist and their number was more related to plasma current than gas-flow rate. The number of anode arc roots increased with increased plasma current. The anode arc root can move forward and backward in the arc plasma jet, and its position was related to current and gas-flow rate. The anode arc root moved forward with increased current, whereas the anode arc root moved forward first and backward with increased gas-flow rate. Based on the finding, a new non-transferred arc model was established. Finally, the anode arc root motion was classified as steady, slight vibration, alternating motion, jumping motion, and multiple arc root modes. These results can serve as a reference for revealing the mechanism of plasma discharge, optimization design of arc plasma jet, and high-quality plasma generation.