Simulation on multi-species vacuum arc considering both ionization-recombination and species diffusion processes

Abstract

The distribution of species is an important micro process in vacuum discharge equipment. This paper focuses on the investigation into the characteristics of species in a vacuum arc based on modeling and simulation technology. The simulation model in this paper considers that the vacuum arc is multi-species including atoms and ions of various categories and ions of various charge states. The model combines the MHD process and the species transport equation, which enables the acquisition of arc parameters as well as species characteristics. In species transport equations, ionization-recombination and species diffusion are the main factors that influence the distribution of arc species. Ionization-recombination is mainly caused by the collisions between ions and electrons. The species diffusion included the influence of an external body force on the ion species. Through this model, the distribution of ion and atom species can be obtained with and without an external transverse magnetic field (TMF). The simulation results reveal that the rise of the Cr concentration in the CuCr arc leads to the increase in triply charged ions with the electron number density, which weakens the Hall effect and enables the current to be distributed more uniformly at the anode. The lighter ions move faster than heavier ions, which results from the difference of the species distribution. Without the TMF, more ions with a lighter mass gather at the anode center than heavier ions. Under the TMF, the deflection of ions with higher specific charge is more significant. According to the comparison, our simulation is in good agreement with the experimental results from other researchers.