Electrical performance of a round bore, augmented, quadrupole railgun

The parallel connected quadrupole railgun has some unique benefits for reducing bore surface erosion when plasma armatures are employed. Unfortunately, these benefits are offset by a relatively small inductance gradient so that large currents are required to develop state-of-the-art driving pressures. To circumvent this problem a set of series connected, augmenting rails have been incorporated in the design of a 40 mm, round-bore, quadrupole railgun. The one meter long railgun was originally designed only for electrical measurements but the design proved so attractive that projectiles were fabricated and a seven shot test series was conducted. The tests consisted of the acceleration of 50 gram projectiles to velocities of 1.5 km/s with a plasma armature. The device was designed to be energized with separate power sources for the bore and augmenting rails to provide maximum flexibility for performance studies. Data from the electrical measurements and the actual firings are presented to compare and contrast the different modes of operation.