Solid ring armature experiments in a transaugmented railgun

The UTSI 2.4 m long, 11 mm diameter, transaugmented (separately augmented) railgun was used to accelerate solid aluminum ring armatures to velocities up to 3 km/s. The armature consisted of a 15 mm long aluminum tube with a tapered nose and wall thickness of 1 mm. The 1.2 to 1.3 g armatures were tested in a series of both conventional and augmented experiments to evaluate performance, transition velocity and transition action. Precise transition location was determined by correlation of muzzle voltage and the armature light emission measured by a PIN diode looking down the muzzle. The electromagnetic forces in this armature were determined using the MEGA 3-D finite element code. The ring armature produces a magnetic squeeze in the insulator plane which, because of the high compliance of the thin ring, loads the ring against the rails to increase the contact force. Augmentation increases the contact force and increases the transition velocity. This armature configuration may have application in all velocity ranges since it appears to operate as a true hybrid after transition with no plasma armature formation.<>