All-electric rifle-caliber launcher with permanent magnet augmentation

The authors discuss the design, construction and performance of an all-electric rifle-caliber railgun. The railgun, pulsed power supply and injector weigh approximately 38 kg. The barrel is 0.5 m in length and has a 5 /spl times/ 10 min rectangular bore. Neodymium-iron-boron permanent magnets provide the augmentation field. Projectiles ranging in mass from 0.5 to 1 g were fitted with both sliding and plasma contacts and were tested in the railgun. The sliding contact projectiles proved to be the most efficient. The pulsed power supply consisted of ten electrolytic capacitors arranged in a type B Guillemin network that were charged to a maximum of 450 V. The maximum railgun current was approximately 15 kA over a 1 to 4 ms time period. The maximum measured projectile velocity was 450 m/s with a 0.5 g projectile. Projectile materials were brass, tungsten, aluminum, titanium, stainless steel, copper, graphite and copper-impregnated graphite and the rail materials were brass, copper, copper-chromium and copper-impregnated graphite. The copper-impregnated graphite was the best material for both the rail and the projectile because of its low erosion rate and relatively low electrical resistivity. The results show that the highest measured railgun efficiency was slightly less than 1 %.