Study of coilgun performance and comments on powered armatures

Electromagnetic launch technology is being developed at Sandia National Laboratories (SNL) for applications such as high-speed transit, military defense, and space vehicle launching. A lumped-parameter circuit simulation code called Slingshot was developed by SNL to simulate launcher performance (B.M. Marder, 2001). This software calculates self and position-dependent mutual inductances, and temperature-dependent resistances to determine the electrical circuit response self-consistently with the equations of motion for the projectile. The software was designed to simulate high velocity projectile applications where an inductively driven armature was desirable. The armature is modeled as series RL circuit to represent a conductive single-turn loop or a coil winding and did not include any sources. However under some circumstances, such as lower velocity designs for missile launchers, a powered projectile may have some advantages. Such coils could be powered by a small onboard capacitor bank, batteries, or through an external supply. This paper will discuss the operation and some of the design parameters for a general coil gun as well as the circumstances under which a powered armature is desirable