Effects of Armature Height and Position on the Performance of Induction Coil Launcher

Induction coil launcher (ICL) is an electromagnetic accelerator that uses Lorentz force to accelerate a projectile with a conducting armature. In this paper, the effects of the height and starting position of the armature on the performance of the ICL were analyzed. Launching experiments were conducted to verify the analysis results. The speed of the projectile converged to a saturated value as the armature height increased. We found that there exists an optimal starting position of the armature for the highest speed. The concept of inductance gradient was adopted to explain the analysis results. It was possible to predict the acceleration characteristics and to estimate the optimal starting position using this concept. Results show that the armature height should be longer than the drive coil height (H
_coil
), and the bottom of the armature should be positioned between (1/4)H
_coil
and (1/2)H
_coil
at the start to obtain the highest speed. The experimental results showed good agreement with the simulation analysis results.