An Algorithm to Couple an External RL Circuit With the Finite-Element Code EMAP3D

Abstract

Electromagnetic launch systems consist of pulsed power, rectification, and launch components. The finite-element (FE) code EMAP3D is used to compute the fields diffusing into sliding electrical contact launch components using quasi-static field equations. FE analysis of the entire launch system, though not impossible, would be a time-consuming process not worth the effort. Circuit theory based on lumped parameters is better suited for the analysis of some of the electrical components such as the generator, rectifier, power conditioning, and delivery components. Circuit theory becomes almost inevitable when one seeks to maximize the power delivered to launch components through impedance tuning techniques. Hence, one is inclined to look at ways of analyzing entire launch systems applying circuit theory to some components and FE analysis to others where detailed fields are required. An algorithm to couple an external circuit with an applied potential difference and prescribed resistances and inductances with a simple railgun is presented in this paper. The railgun is analyzed using EMAP3D. The external circuit is treated using circuit theory. Continuity of current and potentials is maintained through iterative calculations matching the currents and potentials between the circuit and the railgun. The advantages of this algorithm are that it treats the components using circuit theory and field theory separately and shows rapid convergence