Influence of current waveform on rail-gun launching efficiency

In many factors affecting rail-gunpsilas launching efficiency, magnetic energy stored in rail inductance and joule heat consumed in rail resistance are the key. To reduce magnetic energy loss, the mathematical expressions for rail-gun such as electromagnetic force, launching efficiency and breech voltage are given, and the relation between current waveform and launching efficiency is found. Theoretical analysis shows that the launching efficiency with constant current can not be greater than 50% due to magnetic energy remained in the rail; while pulse current is ideal current supply because the magnetic energy losses can be reduced remarkably. To reduce the rail resistance loss, the relation between the launching efficiency and current mode is analyzed through an example. Two distributed energy store (DES) modes, a single pulse current mode and a constant current mode are used in the example, and launching efficiencies with different current modes are compared by simulation. Results show that rail-gun launching efficiency with single pulse current is the highest since the rail resistance loss is the lowest among these current modes, and the efficiency with DES mode can not be improved effectively.