Post-shot analysis of plasma/rail interaction in a small bore load driving EML

The dynamics of an aluminium plasma structure in a small-bore railgun have been characterized using scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) (depth profiling and X-ray spectroscopy) techniques on rail samples exposed to a single passage of a plasma armature driving a load. These analyses suggest the existence of a thick layer of armature material (aluminium in this case) on all segments of the exposed rail surface with composition varying from pure metallic at the breech and oxidized aluminium (Al₂O₃ ) in other areas. The implications of the oxidized layer to railgun operation are yet to be established. However, the presence of oxidized aluminium on the rail surface would modify both the thermal and electrical characteristics of the rail surface in ways that degrade the performance of plasma armatures and may have implications for armature instability and the evolution of secondary arcs