A review of US patents in electromagnetic launch technology

There have been several pioneering railgun technologies documented in patents issued over the last 20 years. In this survey, US patents issued during the period 1980 to 1999 are analyzed. The patents are separated into three categories: novel concepts and designs, materials and fabrication improvements, and better performance and sub-system interfaces. Uses of electromagnetic (EM) launcher technology in military and civilian applications underpin some of the ground-breaking designs such as the omni-directional railgun and the miniature railgun engine igniter. Novel technologies for more efficient EM launchers are also disclosed. It is these efficiency-enhancing launcher technologies and their evolution that are emphasized in this work. Topical areas of interest include muzzle arc suppression, energy recovery circuits, field augmentation, advanced rail and barrel design, ablation resistant insulators, lightweight high L´ launchers, and the distributed energy store electromagnetic railgun. Later, a set of under-explored technologies for superconducting levitated armatures, laser-controlled semiconductor armatures, and hybrid armatures are disclosed