A series wound air core homopolar generator: SWAC for tactical armor applications

The results of a study on generator design for a pulsed electromagnetic (EM) railgun launcher for a 10-shot low-repetition-rate mobile tactical system are presented. A novel design for a series-wound air-core (SWAC) homopolar generator is discussed. A number approaches to the problems associated with multiple-shot operation and high power density are presented. Specifically, designs for a spiral coil group, segmented current collection, active cooling and optimized rotor kinetic energy are addressed. The most significant features of the design are conventional water cooling, low rotational stored energy, and demonstrated materials and fabrication techniques. The resulting power supply consists of two counterrotating SWAC machines with a net energy density of 10 kJ/kg, 60-MJ total stored energy per shot, 2.50 mA peak current at 320 V, and significantly reduced eddy current losses