Numerical investigation on the interaction between droplets and vacuum arc plasma considering ablation cloud

Abstract Droplets in vacuum arc can have significant influence on the plasma characteristics and be harmful to devices such as vacuum ion sources and vacuum interrupters. Especially for the droplets with a diameter of the order of magnitude of 100 μm, the plasma parameters can be significantly affected by the ablation cloud. However, this physical mechanism is still unclear due to the lack of self-consistent theoretical research. This study established a self-consistent model to simulate the interaction between droplets and vacuum arc plasma. Dynamic meshing is used to study droplet movement. The simulation results revealed that the ablation cloud of the droplet with a diameter of the order of magnitude of 100 μm can considerably affect vacuum arc parameters. An increase in the droplet temperature increases the droplet vapor density, which increases friction between the ablation cloud and the plasma from the cathode side. Therefore, the deceleration and temperature rise of the droplet decrease. With the increase of the initial droplet diameter, the ablation cloud area increases, which decreases the electron temperature. However, the droplet temperature and droplet velocity are not proportional to the droplet diameter, which indicates the critical role of ablation cloud.