Experimental Observation and Numerical Analysis of the Arc Plasma Axial Motion in a Magnetically Rotating Arc Plasma Generator

Abstract

To better understand the arc plasma axial motion under an axial magnetic field, a high-speed charge-coupled device camera was used to observe the arc plasma images in a magnetically rotating arc plasma generator. Experimental results indicate that the arc plasma moves towards the cathode bottom as the magnetic field strength increases, while a higher arc current facilitates the cathode arc root to move to the cathode terminus. A two-dimensional coupled model was used to analyze the arc plasma axial motion under different magnetic field strengths. The numerical simulation shows that the arc plasma is axially compressed and curves towards the cathode bottom. It is proposed that the arc plasma structure is derived from the strong backflow from the anode outlet, which is induced by the low-pressure region near the cathode. Moreover, the coupled model predicts the movement of the cathode arc root in agreement with the experimental results. It is inferred that the movement of the cathode arc root is relevant to the energy flux, which is transported from the arc column plasma to the cathode surface.