The effects of projectile injection on rail ablation in arc-driven railguns

The effects of the projectile injection velocity on the rail ablation in a plasma arc driven railgun have been experimentally studied in this paper. The round bore of the railgun has a calibre of 16 mm and length of 0.6 m. The rails and the insulators were made of copper and fiber-glass epoxy, respectively. A helium gas gun was used as the injector which is able to accelerate a projectile of 8 gram to the velocities of 900 m/s. The barrel was connected to the breech of the railgun through an insulated section where two wires were installed to measure the injection velocity of projectile. The experimental results show that the ablation of copper rails can be markedly reduced if the projectile is injected at a velocity greater than 500 m/s. In addition, the current dependence of ablated mass of the rail has been examined for the experimental data without injection. It is concluded that the ablated mass is basically proportional to the peak current density through the rails.