Influencing factors study of armature current distribution at current ramp-up in railgun

Current ramp-up is an important stage for railgun electromagnetic launch system. In lots of launching experiments, a big chunk of deposit aluminum can be found on the rail surface at the start-up position of the armature-rail contact area, sometimes, erosion can even be turned up. The transition at current ramp-up is mainly related to local degradation of armature. The bigger value of maximum current densities at the rail/armature (A/R) interface lead armature local temperature to increase rapidly, which can deteriorate the material property of armature, degrade the static electrical contact performance, and significantly reduce the railgun lifetime. In this paper, for restraining startup transition, several influencing factors of armature degradation and melt are studied basis of current concentration. Rail resistivity, rail dimensions, armature resistivity and the shape of current supply are considered and simulated. At current start up, skin effect and induced current are analyzed, and which are considered as the direct factors of armature's current distribution. Armature current distribution and the maximum current density are obtained and compared for each factor. At last, launching experiments are carried out as the same condition with simulation, the deposition on the rail surface at the startup position of the A/R interface reflect that the different factors influence the current distribution on armature at the current ramp up, and the results are in reasonable agreement with simulation description.