Experimental study on the characteristics of V-type arc plasma torch with four electrodes

The arc plasma is widely used in various fields due to its excellent advantages, such as elevated temperature, high enthalpy, and increased energy density. Under this direction, a four-electrode V-shaped arc plasma torch was developed to increase both the arc power and plasma volume. The arc dynamic characteristics, the volt-ampere characteristics, and the thermal efficiency of the arc plasma torch were systematically studied. From the acquired results, a large-scale, and low-frequency re-strike process between the arc channels was demonstrated. Compared with the common twin-electrode structure, the stability of the four-electrode structure during the discharging process was improved, exhibiting a wider frequency distribution of the re-strike events. The electrode layout may also affect the dynamic evolution process of the arc. However, from a statistical point of view, no significant differences in electrical characteristics were recorded. The four-electrode V-shaped arc plasma torch presented a typical descending volt-ampere characteristic, and the re-strike frequency increased with an increase in the current. A high thermal efficiency (above 83%) was obtained in the range of arc current of 80-200 A. At a current value of 200 A, the jet enthalpy and the average gas temperature can reach 17.41 MJ/kg and 6590 K, and the corresponding jet length was close to 80 cm because of both the high thermal efficiency and enthalpy. The stable discharge process, high thermal efficiency, high jet enthalpy value, and large volume rendered the proposed four-electrode V-shaped arc plasma torch to be suitable for various applications including nanomaterial preparation, metal powder spheroidization, etc.