Investigation of the Armature Contact Efficiency in a Railgun

In the process of electromagnetic launching (EML), armature-rail contact is affected by the start-up contact. Because the location of the pulse current flowing into the armature is determined by that of the start-up contact region, the distributions of the current and electromagnetic force (EMF) in the armature are affected by the start-up contact. In this paper, the start-up contact between the conventional C-armature and rail is analyzed. Additionally, the distributions of the current flow and EMF in the armature are analyzed. The EMF resulting from the electromagnetic analysis is transferred to the structural analysis via a method of electromagnetic-structure coupling, and the distribution of the armature-rail contact pressure is acquired. Some armature contact parameters and the concept of the armature contact efficiency are proposed. The relationships between the contact parameters and the contact efficiencies of armatures with different lengths are acquired based on a series of simulations. To improve the contact efficiency of the armature, a method called “reverse loading” is presented to design an armature with a new profile. The traditional straight armature is replaced with a curved armature, and the results show that the contact efficiency of the armature with the curved profile is greatly improved.