For the vacuum DC circuit breaker

the process of dielectric recovery after arc is an important physical process to determine whether the breaking is successful or not

thus it has been widely concerned by researchers. The main purpose of this paper is to study the development process and influencing factors of the breakdown stage of metal vapor in vacuum circuit breaker by particle simulation. Based on the Particle in Cell-Monte Carlo Collisions（PIC-MCC） method

a model of metal vapor breakdown after arc is established

and the development process of metal vapor breakdown is simulated in two-dimensional space and three-dimensional velocity. Then

the influences of some important factors

such as contact surface temperature

metal vapor density

contact distance

and voltage on breakdown are discussed. The simulation results show that

in a certain range

increasing the density of metal vapor

the breakdown occurs more rapidly; the higher the contact temperature is

the more prone to occur the breakdown is; the higher the peak value of transient recovery voltage is

the faster the breakdown occurs. In addition

when the field strength is constant

the breakdown is not easy to occur for a small opening distance

and when the opening distance is large

the breakdown time is hardly affected by the contact distance.