Investigation Into the Behavior of Armature Ejecta in Electromagnetic Launchers

It is hypothesized that damage to G10 railgun insulators occurs when a very concentrated stream of molten aluminum, which is ejected out of the armature-rail interface, impacts the insulators at 90° angle and acts as a cutting tool that erodes away the material. In order to test this hypothesis, access to the inside of the railgun bore has been made to visually examine the material ejected from the armatures traveling at high currents and high speeds. Peak currents around 1.75 MA were applied in the test regions, and armature velocities around 1.5 km/s were recorded as it passed by the open section of the bore. The use of an argon backfill to suppress oxidation allowed liquid aluminum streams to be observed leaving the armature-rail interface at speeds in excess of 300 m/s. Results on these and related experiments will be presented in this paper.