Numerical simulation of the electric field distribution in point-barrier-plane air gaps

The main aim of this paper is to study the distribution of the electric field in the point-plane air gaps with an insulating barrier in presence of a space charge under AC voltage. The introduction of an insulating barrier in a point-plane gap increases the dielectric strength of the system by changing the electric field distribution in the air gap in general and on the plane in particular. The influence of the barrier is mainly related to the accumulation of charges on its surface on the side of the active electrode. In addition, the variation of the electric field is influenced by parameters concerning the barrier itself, and the configuration of the interval. The simulation was performed with the COMSOL Multiphysics® simulation software based on finite element method. Our hydrodynamic model that we elaborate including a set of nonlinear partial differential equations represents the motion and the diffusion of charge carriers associated with the reactions between them. The influence of several parameters is investigated in detail based on the model. This model has been validated by comparing with the experimental results obtained in the case of a point-barrier-plane system with a distance between electrodes equal to 5cm. The distribution of the electric field predicted by the numerical model is in accordance with the experimental results.