Development of a 40-stage distributed energy railgun

The development process pertaining to the design, fabrication, and testing of a 40-stage free-running arc synchronous distributed energy railgun is presented. Investigation of this type of system will determine the effectiveness of a distributed energy scheme to suppress the plasma restrike phenomenon and increase plasma armature railgun performance. Determined by a computer simulation, the proposed system will have a 1.0 cm ? 1.0 cm square bore cross section and a stage length of 15.24 cm producing a total rail length of 6 meters for 40 stages. A free-arc is utilized to relieve the financial burden of a large stored energy facility. A velocity of 8 km/s is desired to emulate conditions during a high altitude microsatellite launch. To achieve this velocity, pulsed power in conjunction with a low pressure (~ 10 Torr) air environment is required. The pulsed power supplies 15 kJ of energy to provide an armature current (~ 50 kA) for 1 millisecond. A real-time feedback control system will accurately release the stage energy upon arc arrival. Experimental data collected from a 7-stage prototype distributed system is discussed which will mimic the design and operation of the first 7 stages associated with the 40-stage railgun. The copper rail length is 1.2 m long with a 1 cm ? 1 cm square bore cross section and a 15.24 cm stage length. Each distributed energy stage contains a 750 ?F capacitor bank, a thyristor with an anti-parallel diode, and a driver board for triggering. The armature is formed using a plasma injector that is powered by a 40 kV Marx generator. Diagnostics for this examination include rail B-dot probes as well as independent Rogowski coils for each stage. Data collected from the rail B-dot probes will be used to measure the armature position and velocity as a function of time. There is no target velocity for this prototype; repeatable energy module operation, accurate stage triggering, and arc propagation toward the muzzle are the main areas focus. Outcom- es of these initial experimental results will aid the development of the 40-stage system.