Numerical Analysis of a Transposed Multiwired Armature in Electromagnetic Rail Launchers

Abstract

Solid armatures in electromagnetic rail launchers have to undergo severe electromagnetic, mechanical and thermal stresses. These stresses are unevenly distributed in the armature mainly due to the Velocity Skin Effect. Contrasting this effect reduces the peak to average ratio of the stresses and allows better performance of the device. In this paper, the behavior of a transposed multi-conductor solid armature is numerically investigated by the research code EN4EM (Electric Network for ElectroMagnetics) developed at the DESTEC. The code is based on an Integral Formulation that reduces the magnetic diffusion problem in the analysis of a time-varying electric network. The code enables a strong electromechanical coupling and allows accounting for currents distribution in the rails and in the armature due to the proximity and 'ordinary' skin effects, as well as the velocity skin effect. Preliminary computations have shown an improved (more regular) current density distribution in the armature. This allows increasing the total current on the armature without reaching the melting temperature in the armature. Improved performance of the launcher with transposed armature is predicted.