Experiments with brush projectiles in a parallel augmented railgun

One of the main issues of railguns is the ablation of the rails due to the existence of a plasma arc occurring at high currents. To avoid the heat load on the rails it is necessary to reduce the current intensities. The use of a parallel augmented railgun is one method of lowering the current without reducing the electromagnetic force on the projectile. One- and two-brush projectiles have been fired in a parallel augmented railgun with a 15 mm×15 mm caliber and with a barrel length of 1.5 m. These experiments have shown that the maximum kinetic energy at the muzzle-without the transition of the solid contact between the rails and the brush to a plasma contact-can be significantly increased in an augmented railgun. The maximum kinetic energy has increased by a factor of 5 for one-brush projectiles and by a factor of 9 for two-brush projectiles. A model for the electromagnetic force in the augmented railgun and a friction model for the brush projectile are presented. The kinematics of the projectile in the gun are simulated with these models and are compared to the measured velocity. A good agreement is obtained.