Electromagnetic processes and launch efficiency of railgun systems

Detailed analysis of electromagnetic processes in railgun armatures shows that an electromagnetic drag mechanism caused by the generation of eddy currents is an ubiquitous effect in any railgun system. The results of an energy balance analysis allowed us to construct the equivalent electric circuits of railgun armatures. The acceleration in any railgun is equivalent, from an energetic point of view, to charging of a leaking capacitor. Simple numerical evaluations of the value of the electromagnetic drag force show that its role in the acceleration process is unavoidable for typical railgun launcher experimental conditions, although a quantitative evaluation of the drag force is difficult to make. Even discounting any known performance loss mechanism of a non-electromagnetic nature, our study gives a consistent qualitative explanation for all irreconcilable phenomena known from experiments; the saturation of attainable velocities, the degradation of plasma armatures, and the problem of high velocity sliding contact for metal armatures. Possible ways of optimizing railgun acceleration and achieving a higher velocity are discussed.