Numerical Modelling of Vapor Dynamics in Vacuum Arcs between Electrodes with Metal Shield Wall using Moving Particle Method

This paper describes calculation results on copper vapor dynamics in reduced pressure arcs between the copper electrodes with and without a metal shield wall surrounding. Such a reduced pressure arc can be seen during high current interruption between the electrodes in vacuum circuit breakers (VCBs). This arc plasma is established from metal vapor itself from the electrodes. We have originally developed a numerical model for vapor behavior in reduced pressure arcs on the basis of a hybrid method: vapor dynamics including ions and neutral atoms were simulated in low pressure using the particle method of moving particle semi-implicit (MPS) method, whereas the finite volume method (FVM) was used to simulate electron temperature and electro-magnetic fields. The arc behavior is well known to be influenced by vapor dynamics and also the presence of the metal shield wall. Influence of the presence of metal shield wall was here studied on the vapor dynamics, the heavy particle temperatures and the ionization degrees. Calculation results showed that copper vapor was more concentrated around the center of the electrode axis because of the reflection of particles by the wall. Ionization degree was also decreased due to the vapor neutralization.