A SINGLE-ELEMENT MULTIPHASE COMPULSATOR POWERED RAILGUN SYSTEM

This paper investigates multiphase railguns (electromagnetic launchers ) powered by multiphase compensated pulsed alternators (compulsators). The polyphase system offers several advantages over the single phase system. The multiphase compulsator relaxes the strong dependence betwe en the current pulse width necessary for the railgun and the design pa rameters of the generator (number of poles, rotor diameter and tip spe ed) thus allowing the compulsator to be designed for optimum power den sity and electromechanical energy conversion. The paper examines in pa rticular the two phase system. The authors explore different methods o f achieving high acceleration ratios (average to peak) in multiphase r ailgun systems. Some of the methods analyzed are ramping up the field current of the compulsator to counter the increasing impedance of the gun, using a railgun with varying inductance per unit length (L'), and using an external variable inductor in series with the compulsator. S pecial attention is devoted to the external series inductor method whi ch uses a rotary flux compressor (rfc). Several concepts to integrate the rfc and the compulsator into a single element device are discussed . Comparison between the state of the art single phase compulsator pow ered 9 MJ railgun system, currently under fabrication at CEM-UT and a two phase compulsator driven four rail railgun system is also presente d.