Why plasma armature railguns don't work (and what can be done about it)

Abstract

It is noted that conventional plasma armature railguns are limited to velocities of 6-8 km/s by arc restrike. The author argues that to realize the hypervelocity potential of plasma armature railguns, restrike must be eliminated. He describes two promising approaches which are based on demonstrated technology. The near-term solution is some form of circuit arrangement which eliminates current flow in the restrike arc. Both segmented and distributed configurations merit further development, but major issues of electrical and mechanical complexity must be addressed. For the longer term, the development of advanced ceramics coupled with measures to reduce armature power shows promise. Special attention will be required to inject projectiles at a velocity greater than the damage threshold and to perform the plasma armatures to avoid local bore damage. With restrike under control, the only plasma-related limitation will be viscous drag on the armature plasma. Recent MIDI-2 experiments with a hydrogen plasma armature have demonstrated armature velocities in excess of 30 km/s, so armature drag does not appear to be an issue in the 10-20 km/s velocity regime.