The space charge effect on the corona discharge of SF6 gas

In this paper, the characteristics of corona discharge in SF6 gas used as an insulating medium in lots of high-voltage equipments, are simulated by using the finite-element method (FEM) with the flux-corrected transport (FCT) method. The properties of negative corona discharge in needle to plane electrode are analyzed at different discharge stages. For the accurate results, the secondary electron emission by photon and ion as well as Townsend first ionization and electron attachment are considered. The simulation results show that the electric field intensity between anode and ion group decreases according to the electric field distortion by space charge as time goes by. It is also found that the electron density is reduced sharply by the superior electron attachment effect of SF6 gas so that the corona discharge has been extinguished abruptly.