Modeling and Circuit Analysis of an Electromagnetic Launcher System for a Transient Current

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 factors influencing the electrical properties and the performance of the launcher have been investigated. The pulse-forming inductors of the power supply and the rails of the launcher are made of massive conductors showing a prominent skin effect for a transient current. The circuit analysis using constant impedance values has a difficulty in the calculation of the correct voltages between the terminals of the conductors. In addition, the frictional force between the rails and the armature should be considered for a better estimation of the armature motion. To obtain the calculated solutions close to the measured ones, the diffusion of the magnetic flux or current was considered, 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 to 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 the rails of an electromagnetic launcher was introduced in detail, and the comparison of the results between the experiments and modified calculations for the constructed launcher system was described.