A critical factor in the successful operation of an electromagnetic launcher (EML) is the maintenance of good electrical contact between the armature and rail. While there have been numerous experimental and theoretical investigations of armature-rail interfaces, a well-accepted model of the contact conditions has not yet been established. In the current study, we consider the interface between a stationary metallic flat and a translating pin with a hemispherical tip. Operating conditions of the experiments are designed to yield the contact pressures (∼500 MPa) and electrical current densities (∼5 GA/m2) existing in typical EMLs, albeit with much lower sliding speeds (∼3 m/s). Electrical current to the interface is supplied by a programmable 8V/350A power supply. The test apparatus is configured so that the pin can translate continuously along a 1.5 m rail, its carriage being powered by a direct drive linear motor. Loading of the pin against the flat is provided by means of a pneumatic actuator. Current, voltage, load, friction, surface temperature and position are monitored throughout the sliding event. Changes in surface topography and morphology are assessed via optical and stylus profilometry as well as optical microscopy. Arcing and phase change events are observed.

This content is only available via PDF.
You do not currently have access to this content.