Solid-Projectile Helical Electromagnetic Launcher

Helical electromagnetic launchers (HEMLs) can operate at significantly lower currents and higher efficiency in comparison to conventional railgun and induction coilgun launchers. The HEML's versatility is due, in part, to its large inductance gradient which is typically two to three orders of magnitude greater than a conventional railgun and can be tailored to almost any value in that range. Historically, however, HEMLs were not considered practical since they consisted of a hollow projectile (i.e., armature that is accelerated on the outside of a stator coil). This investigation demonstrates, for the first time, a 40-mm bore times 750-mm length solid-projectile HEML, where the armature is accelerated on the inside of a stator coil. The goal of this paper is to demonstrate the practicality of solid-projectile HEML concept and to measure its performance. Numerous successful tests were conducted. The highest velocity measured for a 170-g projectile was 64 m/s.