Two-dimensional current density and temperature development in the return rail of an EM launcher with temperature-dependent properties

A method used to model the two-dimensional current and temperature development in the return rail of an electromagnetic launcher (EML) during launch, incorporating temperature-dependent electrical and thermal material properties, is presented. Due to these temperature dependencies and the nonlinearities they introduce, the derived equations must be solved numerically. Comparisons of the current and temperature responses are made with the results of a previously published constant-property model. This two-dimensional model duplicates the breech responses of one-dimensional analyses and, in addition, provides the detailed structure of the current and temperature sheaths. In particular, application of this model shows that the most severe gradients occur away from the breech, and that they are much in excess of those predicted by one-dimensional analyses