Analysis of the Railguns Contact Resistance Considering Arc Ignition in Contact Surface

Contact resistance is an important parameter that can characterize the contact state and working performance of railguns. Currently, the calculation of contact resistance mainly relies on Holm contact theory, which has a large gap with the experimental results when the armature moves at high speed or undergoes transition. In this article, velocity skin effect (VSE) is considered for calculating the additional contact resistance at high speed. The Townsend discharge model was used to calculate the conditions for the occurrence of arcs, and Kushner’s arc resistance model was used to analyze the phenomenon of arcs in the contact gap of electromagnetic railguns. Thus, the contact resistance of railguns, considering the arc resistance, VSE contact resistance, and Holm contact resistance, is calculated. The results show that the arc resistance may exceed 1 m $\Omega $ under certain conditions, which is much larger than the Holm contact resistance between solid surfaces, and becomes the dominant component of the contact resistance when transition occurs. The results of this article can help to explore the contact and transition damage mechanisms of electromagnetic railguns.