Guidelines for the design of synchronous-type coilguns

Smooth acceleration and evenly distributed mechanical and thermal stresses can be achieved in a coilgun type of electromagnetic launcher by the interaction between an electromagnetic wave-packet traveling along the barrel and a moving cylindrical conductor (sleeve) carrying a system of currents. The barrel consists of an array of cylindrical coils energized by polyphase currents; upon the sleeve is impressed a sinusoidal distribution of azimuthal currents. Design guides and scaling laws are developed for such a launcher. It is shown that muzzle velocities up to 10 km/s might be attainable with a barrel length of less than 15 m with high efficiencies. However, for velocities far in excess of that range, the need to maintain the physical integrity of solid armatures leads to barrel lengths which may be impractical for most applications.