Observation and simulation of armature contact performance in the cannon-caliber electromagnetic gun

Major components developed under the Cannon-Caliber Electromagnetic Gun (CCEMG) Program are presently undergoing tests at the U.S. Army Research Laboratorg (ARL) located at Aberdeen Proving Ground (APG), MD. The CCEMG launcher is a series-augmented barrel 2.25 m in length and has a rectangular bore cross section of 17.3 mm/spl times/37.3 mm. The system is designed to operate with a peak current of 835 kA, a launch package mass of 185 g, and an exit velocity of 1,850 m/s. CCEMG is a multishot system demonstrator. The test results we discuss here are for single-shot operation. The muzzle voltage in an augmented launcher contains contributions from the fields due to the augmenting turn. These imposed voltage terms tend to mask the transition of the armature contact, thereby making the transition event less discernable than in a simple railgun. The Army Railgun Modular Simulator (ARMS) computer code has been modified to provide a one-dimensional (1-D), lumped parameter model of the launcher and contact wear at the armature-to-rail interface. The CCEMG launcher data are used to further validate the ARMS code and contact wear model. Additionally, a two-dimensional, transient finite difference (2-D TFD) model is used to assess heating in the armature. In this paper we present photographic and electrical data from two shots in which armature performance is simulated.