Electromagnetic launch experiments using a 4.8 MJ pulsed power supply

Abstract

After preliminary tests using a small 25 mm-caliber electromagnetic launcher, a larger mid-caliber launcher has been designed and fabricated. The launcher has a rectangular bore of 40 mm × 50 mm where the rails are separated by 50 mm each other and are 5.6 m long. To deliver an electrical current to the launcher, a new 4.8 MJ pulsed power supply (PPS) consisting of eight 600 kJ segments has been constructed. The 600 kJ segment is a basic building block of PPS operated independently. It contains a controller, a charger, a safety circuit, and six 100 kJ unit modules. Each unit module in the segment is composed of a 100 kJ capacitor bank, a thyristor switch, a crowbar diode, and a pulse-forming inductor. The modules in a segment are charged to the same voltage, but they are designed to have different triggering times to make a flexible shape of current waveform. Electrical parameters of the PPS were determined through the discharges of the unit modules, and those of the rails were done by launch experiments or short circuit tests at the ends of the rails. Launch experiments have been done using several current waveforms. The current of 1 MA in a few ms made the armatures of several hundred grams in mass accelerate to velocities near 2 km/s. In this paper, the design and basic performance of the constructed PPS and the electromagnetic launcher are presented.