Switch characteristics for a high efficiency 20 kJ electromagnetic launcher

During the development of a high-efficiency single-turn electromagnetic launcher, it became apparent that the main limiting feature was the closing switch used to connect the launcher coil to the charged capacitor forming the initial energy source. Both experimental and theoretical considerations established that, even by the time the projectile attained the terminal velocity, more than 30% of the initial capacitor energy had been absorbed in the simple and low cost nail switch that was being used. In an attempt to maximise the launcher efficiency, the characteristics of five different switch technologies were investigated. The initial capacitor voltage could be up to 30 kV and the launcher coil current peaked at up to 900 kA in about 1 /spl mu/s, and in addition to the nail switch, those considered were triggered spark gaps, nail switches, surface switches, metal-to-metal detonator switches and solid dielectric switches.