Numerical Simulation Of Large-Current Vacuum Arc Plasma

Characteristics and controlling technologies of vacuum arc are very critical for theperformances of vacuum interrupter. Due to the complexity of vacuum arc, at present,people still cannot understand the physical process of vacuum arc completely and distinctly.Although pare of the parameters and characteristics of vacuum arc can be obtained throughexperiments. it still is not enough to reveal the physical process of vacuum arc completelyonly through experimental researches. By means of reasonable modeling and simulation,persons can synthetically consider the transport process of arc plasma and the influence ofrelated factors. Since it is a kind of effective tools for deeper researches of vacuum arc. Inthis dissertation, major researches are emphasized on modeling and simulation the vacuumarc under different states; it can enhance our understanding of vacuum arc. Simulltaneously,it also can provide theory basis for design and optimizing of vacuum interrupters.In this paper, the existing vacuum arc models are analysed and summarized firstly.The vacuum arc magnetohydrodynamic model is established according to different statevacuum arc characteristics.When the ion is subsonic state,boundary conditions of cathodeand the anode sides must be set according to computing fluid dynamics(CFD)theory.Moreover,the influence of kinetic energy of ion and electron and ion viscocity isconsidered. Based on the computational fluid dynamic(CFD)software FLUENT whichis re-developmented by Visual C++, fluid equations and electromagnetism equation,electron energy equation are coupled and solved, simulation of vacuum arc MHD model isrealized successfully.The vacuum arc is simulated above model established. Simulation results show thatthe maximal plasma pressure and plasma density of vacuum arc appears near the cathode side,but the minimum plasma velocity and Mach number of vacuum arc appears near thecathode side. The vacuum arc MHD model also is simulated in different arc current andelectrode distance cases, the results show that along with the increase of the electric arccurrent, the anode axial current density distribution is uneven, electronic temperature andthe plasma pressure increase as the electric arc current increased,while the change of iontemperature is not obvious; As the open distance increased, the axial current density,theelectronic temperature and the plasma pressure increase, while the change of iontemperature is not obvious.