A finite element method for the determination of space charge distributions in complex geometry

Electrical breakdown in insulators very often initiate near high field regi ons of the structure, as found near small-radius impurities or at electrode defects. This is attributed to the development of localized space charges. For this reason many efforts have been made to determine such charge. Vari ous techniques are now available, but they are not directly applicable to c omplex geometries where it is difficult to determine analytically the field configuration and thus the relation between the measured variables and the space charge distribution. To solve this problem, we propose to use a nume rical simulation using a finite element method (FEM). In this paper we desc ribe how it can be implemented in the case of the pressure wave propagation (PWP) method. It is shown that measured signals in insulating samples with divergent electric field regions are well fitted by simulations. We show t hat this allows for the determination of space charge distribution in such samples.