Dynamic behaviors of SF6 discharge process in short parallel-plate gaps

The two-dimensional hydrodynamic discharge model is presented based on the hydrodynamic mechanics theory and gas discharge characteristics, with a uniform applied field, during the discharge process of SF₆ at atmospheric pressure, and it is established by adopting Poisson equation in conjunction with the continuity equations for electrons, negative and positive ions, besides, the photo - ionization is also considered in the proposed model. The Finite Difference-Flux Corrected Transport technique is used in numerical simulation of discharge process, in order to improve the accuracy and efficiency. Then the gap-space electric field distribution, space ions distribution are revealed from the microscopic mechanism, and the evolutions of the charged particles are obtained in detail, furthermore, the tempo-spatial critical point of the avalanche-to-streamer in this model is discovered, the influence of applied voltage and initial plasma charge density on the streamer characteristic are also investigated. The results show that the initial plasma charge density is closely related to the gradient slope of the gap-space electric field distribution and electron density distribution, meanwhile, the electric field strength, the propagation velocity and charge density of the streamer head increase with increasing applied voltage. Above results analysis can be in favor of further study of the discharge mechanism and provide the theoretical support for electrical equipment designed.