A Microscopic Study of Before-Arc Process in Metal Vapor Plasmas Proximal Cathode Region. Part I Formation of the Proximal Cathode Region

Abstract

Metal vapor arc in vacuum breaker is a very complex phenomena and the researches on the process of arc creating are the effective method to improve breaking ability. By the theoretical study and numerical simulation, exploring the formation of plasma sheath near the cathode, charged particles energy distribution and influence elements in before-arc process are the fundamentals of this paper. Before-arc process is the fundermental of arc energy and the proximal cathode region is the important area for vacuum arc forming, so before-arc process of metal vapor arc was simulated here. The modification to electron motion produced by the interaction between charged particles and plane electrodes and both elastic and charge exchange collisions between electrons and neutral gases were considered here. The copper cross section adopted here was related to the particle energy. The tracks of electrons were traced until they reached to the anode surface. Based on this method, the formation of proximal cathode region and some microscopic parameters were simulated here. The results show that the collision between charged particles with the electrodes is the necessary condition in proximal cathode regions formation.