3-D field analysis in tubular induction launchers with armature transversemotion

In this paper the transition between the sections of a generator driven ind uction launcher is investigated. During the transition a possible mismatch of the currents in the sleeve nifh the driving coils currents can give rise to strong braking force. If the sleeve is not in coaxial position with the barrels, forces in the transverse direction of motion can produce contacts ,vith the flyway tube. Transverse motion of the sleeve has to be considered, The equations of moti on are derived assuming a rigid projectile and a flyway restoring force tha t is proportional to the local deformation. A full 3-D analysis, required because of the departure from the coaxial con figuration, has been performed by means of a computer code based on an inte gral formulation of the Maxwell equations; the resulting equations are thos e of an electrical time-varying network Simulations of the behaviour of the system have been performed to search for the optimal initial position of t he sleeve in the second section. The results show that smooth transition be tween the sections is obtained if the energization of the coils of the seco nd section is done in correspondence with the proper positions of the sleev e. Under these conditions the motion is characteryzed by the greater muzzle velocity.