Analysis of non-linear electrostatic devices by a hybrid FEM-MOM formulation

The equilibrium theorem in terms of equivalent surface charges and normal electric flux density is used to obtain a hybrid FEM-MOM formulation for the analysis of electrostatic devices eventually characterised by the presence of non-linear dielectric materials. Dielectric materials are enclosed in fictitious surfaces where a distribution of normal electric flux density and equivalent charge is assumed. The equivalence theorem is used to obtain interior and exterior problems coupled by the interface continuity conditions applied to tangential components of electric field and to normal components of flux density. The finite element method is used to enforce the interface conditions. The proposed method has been applied to the evaluation of the field produced by a non-linear dielectric sphere in a uniform field and to the evaluation of capacitance in systems with inhomogeneous dielectrics.