Reduction in fluctuation of the accelerating force in linear induction launchers

Abstract

In a linear induction launcher, both the barrel and the projectile are of finite length. This causes the force-displacement curve to have a jagged shape. The reasons are: the barrel is partitioned into sections; end effects are present; dc components exist in the input currents; and the drive coils are of finite width. The first three factors were dealt with in our previous publications. This paper describes how to improve the performance of a four-section linear induction coil launcher, powered by synchronous generators, by redesigning the drive coils so that they may be fed by a five-phase source rather than the customary three. The paper presents the drive-coil design criteria, the reasoning behind the selection of the firing sequence for each of the four sections, and the improved accelerating force curve.