Investigations on magnetic field in the interface regions between plasma armature and rail electrodes in a railgun

The key to controlling rail ablation lies in the interface regions between plasma armature and rails. The distribution of plasma in this region is affected by many factors, the magnetic field being the dominant one. In this paper, we analyze the magnetic field generated by rails and plasma armature in the interface regions, study the pattern and distribution of plasma near the interface and show the affect of magnetic field on plasma distribution and on the energy input to the rails. In order to reduce the initial ablation of the rail, we designed magnetic field coils outside the beginning part of the rails of our railgun. The coils enhance the initial magnetic field and increase the uniformity of the current distribution in the rails. Based on results from experiments and theoretical analysis, we propose a reasonable configuration of magnets and plasma armature.