Numerical simulation of negative point-plane corona discharge mechanism in SF₆ gas

This paper presents the results of the numerical simulation of negative corona discharge in SF₆ at 0.4 Mpa for a point-plane configuration. A 2D axisymmetric model considering three charged species has been investigated with an applied voltage equal to -25 kV. Three drift-diffusion equations coupled with Poisson's equation were solved simultaneously to obtain the temporal and spatial properties of Trichel pulses. The distributions of charged species at different instants of time and the time-dependent total number of charged species have been determined. The characteristics of current pulses with voltages varying from -24 kV to -27 kV were compared and it has been found that the characteristics of the current magnitude and frequency are similar to those in air. The effects of the model coefficients - the ionization coefficient, the attachment coefficient, the mobility of charged species and the secondary emission coefficient - on the characteristics of current pulses have also been studied to investigate the sensitivities of the pulse parameters to these coefficients.