FEM/MOM formulation for the analysis of current distribution in rail launchers

This paper presents a numerical formulation for the analysis of sliding contacts between moving conductors based on a hybrid FEM (finite element method) MOM (method of moments) technique. The use of the equivalence theorem allows splitting the complete problem in a number of interior problems and in an exterior one. The coupling of these problems is performed via the imposition of the continuity conditions of fields on the fictitious surfaces that enclose the moving conductors. Suitable additional boundary conditions are imposed on the sliding surfaces in order to ensure the proper current flux through the contacts. The proposed formulation is applied to the analysis of the performance of a rail-launcher. The results of the simulations show the capability of the formulation to take into account the characteristic phenomena of these devices and in particular the presence of the velocity skin effect. Comparisons between the results obtained by the proposed formulation and by other methods are reported.