Analysis of Electric Field Distribution in Capacitors’ Dielectric with Cavities

Cavities in dielectric greatly impair the performance of capacitors, especially the life and so further affect the primary power systems in fusion energy systems. Thus, the electric field distribution in dielectric of capacitors with cavities was studied. A simplified elliptical cavity model in dielectric was built in this paper and finite element analysis was utilized to solve the electric field distribution problem. Simulation results show that the electric field near the cavities will be enhanced with a factor of k. The enhance factor k will rise with the increase of the relative permittivity of capacitors’ dielectric. The influence of the cavities’ shape on enhancement mainly results from the curvature. When the cavities possess higher curvature, the enhancement will be strengthen. Also, the orientation of the cavities affects the electric field significantly. The enhance factor k decreases with the decreasing of the angle between the major axis of ellipse and the external electric field direction.