A first report on electromigration studies at a model copper-aluminum railgun contact

Abstract

10A) was necessary to produce the large current densities typically found in railguns, and was able to simulate the skin effect on both the Cu rails and Al armature under static, long-term testing conditions. In this method, the effects of electromigration were discerned clearly, in dissociation from various movement related damage phenomena. The aluminum from the armature quickly reached its melting point via Joule heating due to high contact resistance at the armature-rail contact. Once liquid aluminum was formed, it rapidly migrated along the copper rail towards the negative terminal. This transport of liquid aluminum along the copper rails was attributed to electromigration of the liquid under the influence of the direct electric field. Once the aluminum began to be transported along the rail towards the cathode terminal, it alloyed with the copper rails and the resistance steadily increased in the circuit. Electromigration is shown to be a contributing factor to the degradation of aluminum armatures performance and copper rails lifespan in the railgun.