Small bore railgun activities at KSL

A series of railgun experiments was performed with the view of preventing secondary arcs in using a plasma armature. Several pairs of small holes were drilled through rail insulators to expel neutral gas which consists of bore materials vaporized by high temperature plasma. These small holes are referred to as spout holes. When the railgun was operated with them, secondary arcs seldom occurred, and projectile acceleration performances were considerably improved. Three series of successive shots experiments were also performed to investigate the influence of bore damages on the acceleration performance. In each series, bore components were only cleaned, and were never refurbished or reamed. Damages of bore components were also evaluated after ten shots. The results of copper-tungsten alloy were quite satisfactory, as the projectile velocities were relatively steady at each repetitive shots, and the amount of erosion was very small.<>