EXPERIMENTAL COMPARISON OF CONVENTIONAL AND TRANS-AUGMENTED RAILGUNS

A 2.4 m long, 1 cm diameter round bore railgun was constructed at UTSI to perform careful experiments which compared the performance of conventional and trans-augmented plasma armature railguns. The gun was constructed with copper rails and G-9 insulators and had a single augmenting turn. Two separate 240 kJ capacitor banks and inductors were used to provide current independently to the armature and to the augmenting turn. The barrel was fitted with an array of B-dot probes spaced 10 cm apart to provide good resolution of the plasma armature characteristics. A MAVIS electromagnetic transducer was used to provide accurate measurements of the muzzle velocity. The gun bore was lapped full length from the light gas injector to the muzzle between each shot to provide a uniform, high quality bore surface for each experiment. Conventional railgun experiments were performed over a range of currents to characterize the base performance of the railgun and to provide data for the development of ablation drag and thermal propulsive models. Experiments were then performed for a range of (separately powered) augmentation currents but with railgun currents equal to those used in the conventional experiments. The enhanced performance provided by augmentation was found to be significantly less than predicted by theory, even though the railgun operated without the formation of secondary armatures or restrikes.