Modeling of CuCr contact vacuum arc with consideration of its components

Abstract

This paper involves the simulation of vacuum arc under composite (CuCr) contact. A three dimensional model is developed and we have considered the ionization process as well as recombination in the vacuum arc. The species transport equations, in which the fraction of each component is calculated, provides the distribution of various atoms and ions in vacuum arc. The model describes ions and atoms as two different processes considering that ions are influenced by self-generated magnetic field. Atoms play an inferior role in the process of vacuum arc. They gather in an ‘atom layer’ whose thickness is no more than 1mm and outside the atom layer the density of atoms declines by at most 5 orders of magnitude. The ionization process is dominated by electron temperature. The distribution of ion species is closely related to the degree of ionization. At cathode, singly charged ions are dominant. From cathode to anode, ions are ionized so that doubly charged ions become the major component at anode where singly charged ions reach their minimum density. Finally, the ionization rate is also influenced by the ionization potential of each component, so the fraction of Cr1+ is smaller than Cu1+ while Cr2+ is larger than Cu2+ in the anode center.