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.