Experimental observation of the rail resistance contribution to muzzle voltage [in railguns]

In 1994, Dreizin and Barber presented an analysis of the muzzle voltage developed in a railgun with a solid contact armature. They showed that there is a significant contribution to the measured muzzle voltage arising from the current flow in the rails ahead of the armature. They further argued that this voltage is influenced by velocity skin effect and that it may become the dominant effect on muzzle voltage at high velocity. The results of that paper, although on solid theoretical foundations, generated some controversy because many previous investigations of armature behavior had obtained good agreement between theory and observation without taking this term into account. In this paper, a novel experimental technique is described that permits direct observation of the effect of precursor rail current on muzzle voltage. The observed magnitude of the voltage is in agreement with the estimates provided by Dreizin and Barber, including the contribution of velocity skin effect.