Appraisal of Rapid-Fire Electromagnetic Launch Effects on Ceramic Targets

With the current developments in electromagnetic launch technology, railguns have become more suitable for multiple applications. This paper explores the delivery of a rapid succession (several per second) of projectiles to a 100 cm
²
ceramic target. We test whether a series of impacts on a target will cause more damage than a single impact of equivalent energy. This premise is based on the fact that the target is damaged at the first impact and is thus weakened when subjected to subsequent impacts. We use a series of physical experiments to evaluate this hypothesis, and to assess the magnitude of the effect. The launch system is the SR\3-60 railgun, developed by the French-German Research Institute of Saint-Louis, which comprises three pairs of rails mounted in a hexagonal geometry. Each pair of rails is connected to a 150 kJ capacitive power supply with 2 m acceleration length. The SR\3-60 can be used to generate very flexible multi-hit impact sequences. Tungsten-tipped projectiles were launched against sintered alumina (Al
₂
O
₃
) targets. In the first set of experiments, the damage caused by a single projectile is compared to that caused by a pair of smaller projectiles, each having a fraction of the weight of individual projectile and fired at a greater velocity, so that a pair of impacts carries the same kinetic energy as an individual one. This was also extended to three projectiles. High-speed video imagery was deployed to capture fracture development in the target. Comparisons are performed at a range of subsonic velocities.