Analysis of Electron and Heavy Particle Velocities as Function of Ambient Pressure Changes in Vacuum Arc

Vacuum arc cathode spot is used in industrial applications such as oxide film removing. Oxide film processing using a vacuum arc cathode spot does not emit secondary exhaust and fast. However, the arc discharge under atmospheric pressure melts the surface of the base material, it is necessary to use a chamber to create a high vacuum environment. To solve these problems, the movement of vacuum arc cathode spot needs to be elucidated. In this research, a simulation was developed to realize an oxide film removing method in a low vacuum environment. Thermo-Field (below T-F) electron emission caused by the sheath electric field generated by the charge separation of ions and electrons and rising temperature of the cathode have been proposed as one of the cathode spot movement factors. However, in the one-temperature, one-fluid analysis based on the assumption of local thermal equilibrium, there is a problem in that the flow velocities of electrons and heavy particles, which behave differently, are calculated as the same. Hence, the flow velocity of ions, which determines the direction of retrograde motion of the cathode spot, is not considered. Development of simulations considering the 2T-2F model with energy and momentum conservation equations for heavy particles and electrons is needed to elucidate the factors of cathode spot movement. Moreover, the electron and heavy particle velocities as function of ambient pressure changes in vacuum arc were analyzed using a 2temperature-2fluid (2T-2F) simulation model.