Transient 3-d simulation of an experimental railgun using finite element methods

Today progress in railgun research is usually achieved experimentally with support from simulations. The finite element method (FEM) is one popular and wide spread tool in many fields of research. But the transient computation of a 3-d model of a railgun, taking into account the time evolution of the acceleration process, coupling the electromagnetic fields to the moving projectile, is a complex task. Such a simulation involves large gradients of the electromagnetic fields, large structures of the order of meters with areas of interest in the sub-millimeter range, a fast moving projectile causing a rapid change of the current flow through the volume in the next vicinity of the contact. Nevertheless, recent developments in FEM tools make it attractive to attempt such a simulation. At the French-German Research Institute of Saint-Louis the electromagnetic acceleration group uses the program COMSOL to set up a transient 3-d simulation of a small caliber railgun. Here the implementation of the railgun as COMSOL model and the comparison to experimental data is presented.