Metal vapor as the background gas causes frequent collisions of charged particles in the vacuum arc chamber

and the thermal ionization effect can change the plasma density in post-arc stage

which has a great influence on the dielectric recovery process of the intermediate-frequency (IF) vacuum arc. In the present work

multi-target tracking techniques have been applied to dual-view arc images when the IF current fails to be interrupted firstly. According to the spatial mapping relationship

metal droplet ejection process is three-dimensional constructed

and a velocity of 10~20 m·s-1

a pressure between 1~5 MPa

the maximum metal vapor number density of 1023 m-3 in the surface of metal droplet inside the vacuum chamber are obtained

realizing non-invasive measurement for number density of metal vapor. Then

the particle-in-cell-Monte Carlo collision (PIC-MCC) model is modified. Thermal ionization on sheath growth is taken into account in the modeling process

and Saha equation is used to modify the initial plasma density. Finally

the modified PIC-MCC model can predict the occurrence of IF post-arc breakdown when the metal vapor increases from 1018 m-3 to 1023 m-3

which is consistent with the experimental results

proving that thermal ionization of metal vapor has an important impact on the characteristics of IF post-arc dielectric recovery.