Modeling and circuit analysis of an electromagnetic launcher system for transient current waveforms

Abstract

An electromagnetic launcher with a 4.8 MJ pulsed power supply has been fabricated, and experimental tests were started. Through the experiments and calculations, the effects influencing on the electrical properties and the performance of the launcher have been investigated. The electromagnetic launcher system includes pulse-forming inductors in the power supply and rails in the launcher which are made of massive conductors showing a prominent skin effect for a transient current. For these conductors constant impedance values or those defined per unit length have difficulties in calculating correct voltages appearing between the terminals of them. In addition, the frictional force between the rail and armature could not be ignored for a better estimation of the armature motion. To obtain solutions close to the measured ones, the diffusion of the magnetic flux density or current density was taken into account, and the history of the armature motion was reflected in the electrical modeling of the rails. These effects were implemented as voltage correction terms in the circuit equations with the help of the electromagnetic responses for a step-function current. In the equation of the armature motion a reasonable form of the frictional force was modeled considering the velocity skin effect and the structural analysis. In this paper, the application of the voltage correction method into rails and the calculated result of the modified circuit equations for the constructed electromagnetic launcher system are presented.