Direct-current arc plasma which is applied in plasma wind tunnel and solid waste disposal is required to possess the characteristics of high power

wide-range variable power

and long-life electrodes in air. To meet these requirements

we experimentally researched and designed a magnetic double-chamber air plasma torch.Based on electrical characteristic experiments and data

the influences of parameters such as current

gas flow rate and distribution ratio on arc voltage and the quantitative expression were acquired. The axial motion characteristic of the arc spot was investigated through the ablation traces on the internal face of electrodes under different currents

gas flow rates and distribution ratios. Results show that the flow condition can decide the arc root axial position

and the flow rate distribution can influence the arc root axial position of the inner electrode. Moreover

the circumferential motion of the arc was investigated by a high-speed camera. The circumferential rotation speed of certain condition was calculated and the rules of micro/small arc distributaries were captured and analyzed from images.