Molecular Dynamics Simulation into the IoN Effects on the Self-Sustainment of Cathode Spots

The understanding of cathode spot behaviors is crucial for mitigating contact erosion and enhancing dielectric strength of vacuum circuit breakers. In this paper, a Molecular Dynamics (MD) model is developed to simulate a local surface area of a cathode spot on the copper contact. The evolution of atom loss rate is utilized to represent the development of a cathode spot. The spot stability, which is observed as the stable growth of the cathode spot, is represented by the stabilized atom loss rate under the plasma effects. This model allows the analysis of effects of the leftover plasma ions and back ions on the stability establishment and self-sustainment of a cathode spot. The validity of this model is confirmed through a comparison between the simulated atom loss rate and the measured ionic erosion rate in experiments.