Observation of inertially-driven thermo-electro-dynamic mass loss from an electromagnetically accelerating armature

Abstract

The reasons for the heavy mass losses usually observed to occur from various parts of recovered solid armatures, even in cases where there was no transition, remain unclear. We earlier suggested that the losses could result from strong non-uniformities in the distribution of thermodynamic, electrical and dynamic parameters in the body of the accelerating armature, the so-called TED effects. As a consequence, some surface areas of the armature can break away from the main body to be either ejected forward or to lag behind by inertia. This paper presents ultra-high-speed camera sequences demonstrating continuous inertial mass loss from the root of a C-shaped armature, where local current concentration gives rise to a strong heating of the material. The mass loss is particularly intensive when launched on the rails coated by an In-Ga eutectic. This may imply that the current concentration is stronger in the rear part of the armature contact surfaces.