Investigations on Armature Jerk for Different Current Pulse and Rail Geometries in an Electromagnetic Railgun

A projectile attached to an armature in a railgun is pushed with a very high force to reach high kinetic energy. To provide higher forces, either single or sequential switching of pulse-forming networks is performed for the current generation. The force profile and, in turn, the jerk on the armature are affected by the shape of the current pulse. In this article, the effects of jerk on an armature are studied by looking at the effects of current slopes and inductance gradients. In this work, conventional jerk equations are presented, and novel analyses using the jerk equations are derived. The finite element method is used to simulate different rail shapes, and from these simulations, jerk is calculated. An analytical model of the conventional railgun system is also simulated and presented with finite element results for comparison from a jerk analysis standpoint. More studies are performed by feeding conventional railgun geometry with current pulses that have different rise and fall slopes. A trade-off between muzzle velocities and armature exit times is uncovered from a current rise or fall slope standpoint.