Behaviors of plasma armature in the augmented railgun using a permanent magnet

Augmentation of the magnetic field for electro-magnetic railguns is a quite effective method to suppress the ablation of bore materials since it allows to decrease the plasma armature current without a decrease of the Lorentz force for the acceleration. Another constructive effect of the augmentation on a plasma armature was observed in our experiment, that is to say, an external magnetic field for the augmentation compresses the plasma armature in the axial direction and suppresses the broadening of the plasma armature. In this paper, the behavior of plasma armature in the augmented railgun using a permanent magnet is investigated in comparison with that in the railgun without the augmentation.