Applications of coilgun electromagnetic propulsion technology

Exciting and important applications of pulsed power and high voltage technology are found in the growing area of electromagnetic launch and propulsion. These applications include small-scale, precision staging devices (magnetically driven), low-speed, large mass catapult launchers, low-speed and high-speed trains, high-speed, long-range fire support naval guns, and the futuristic application of high-speed, direct satellite launch to space. The force requirements range from a few Newtons to millions of Newtons, and the pulsed electrical power requirements range from kilowatts to gigawatts. For repetitive operation, the average prime power requirements range from a few watts to megawatts. The principal technical challenges for such propulsive devices and motors are achieving high thrust and high coil strength, producing and controlling high power levels, and maintaining good weight, volume, and efficiency characteristics. These challenges will be discussed, using coilgun mass launcher and pulsed linear induction motor technology examples. Basic parameters for a long-range fire support coilgun are a muzzle velocity of 2.0 to 2.5 km/s, with a projectile mass of 20 to 60 kg. The kinetic energy is thus around 100 to 200 MJ. To achieve the pulsed power needed for launch from a barrel of less than 20 m, peak coil voltages and currents on the order of 40 kV and 500 kA to 1 MA are needed. Train propulsion is somewhat lower in power demand. The kinetic power for a typical low-speed urban Maglev system would be in the range of 500 kW average power, driven by a power source of some 25 kV peak and 50 A peak. The added requirement of low weight and small volume power conditioning make this application challenging as well. The challenges and solutions for high-voltage power conditioning system designs are reviewed from these examples.