Efficiency and Scaling in DC Electromagnetic Launchers

Efficiency and scaling relationships for DC (i.e., non- induction) electromagnetic launchers (EML's) are presented and discussed. Efficiency and scaling relationships for these types of launchers are easily generalized since their principle of operation is the same, namely the production of an electromagnetic force via a spatial change in inductance. Electromagnetic force, efficiency, back-voltage, and kinetic power are given in terms of electrical circuit parameters. A comparative analysis of the efficiency and scaling relationships for these types of launchers is given and includes EML geometries such as conventional railguns, augmented railguns, and helical coilguns. The comparative analysis results are performed in terms of the launcher's inductance gradient, physical dimensions (i.e., armature- stator diameter and length), resistive losses, local energy storage (i.e., inductive), and armature velocity. A survey of recent electromagnetic launcher results is performed and compared to the theoretical predictions.