Melting and Cavity Growth in the Vicinity of Crack Tips Subjected to Short-Duration Current Pulses

The current-carrying conductors in an electromagnetic launcher are exposed to high currents that last for a few milliseconds. Surface cracks on the rails can generate large gradients in current in their vicinity and may result, in some instances, in localized melting and expulsion of rail material. Here, we report the results of a study in which the mechanical and electrical parameters of the process were monitored as a function of time and the evolution of melting and ejection was examined through high-speed photography.