Concerning the Design of Capacitively Driven Induction Coil Guns

This paper is concerned with the design of capacitively driven, multisection, electromagnetic coil launchers, or coil guns, taking their transient behavior into account. A computer simulation based on the viewpoint of lumped parameter circuits is developed to predict the performance of the launcher system. It is shown that a traveling electromagnetic wave can be generated on the barrel by the resonance of drive coils and their capacitors. More than half of the energy initially stored in the capacitor bank can be converted into kinetic energy of the projectile in one shot, and an additional quarter can be utilized in subsequent shots, if the launcher dimensions, resonant frequency, and firing sequence are properly selected. The projectile starts smoothly from zero initial velocity and with zero initial sleeve current. Section-to-section transitions which have significant effects on the launcher performance are also discussed. Experimental results were obtained with a small model and are in good agreement with theoretical predictions.