High transition velocities for solid armatures in the 10-mm MTR railgun

The transitioning of a solid armature on the Materials Test Railgun (MTR) was studied, and data on high-velocity transitions were analyzed. The railgun has a 10-mm square bore, is 0.6-m long, and is designed with a bolted construction for experimental flexibility. Solid 7075-series Al alloy armatures were accelerated to 1.75 km/s, and transition was observed at approximately 1.3 km/s. These 3-g armatures were designed in a U-shaped configuration. The railgun was driven by a stored energy of 200 kJ from the USA ARDEC (Armament Research Development and Engineering Center) 10-kV capacitor bank power supply. The test configuration, armature design, and shot data are provided. The muzzle voltage data were analyzed using model equations for the transitioning of the solid armature to a hybrid armature with arcing contacts. The data clearly show the development of the voltage as a continuous process involving the various phases for the contacts and the model reflects this behavior. >