Direct Observation of Anode Arc Root Behaviors in a Non-transferred Arc Plasma Device with Multiple Cathodes

To investigate the anode arc root behaviors, a non-transferred arc plasma devices with multiple cathodes is designed in this paper. A novel setup to investigate the dynamics of arc root is developed. Based on high speed photography and voltage waveform analysis, anode arc root behaviors are captured for the steady, takeover and restrike arc modes. The transition of a single arc root, the coexistence of multiple arc roots and the evolution of multiple arc roots are herein investigated. Results show that anode arc root behaviors for these three arc modes are quite different. The restrike, takeover and steady modes correspond differently to the longitudinal motion of single root, circumferential motion of a single root and stationary multiple arc roots, respectively. Moreover, contrary to past experimental results, the stationary multiple arc roots which exist on the anode just within the nozzle entrance and the process by which they form, are demonstrated for the first time.