Resonant shield concept as alternative solution in railguns

This paper deals with shielding resonator structures for possible application in electromagnetic rail launchers. The main aspects of the resonant shield are revisited via the spatial averaging concept of macroscopic quantities and of the effective magnetic behavior. In particular, it is recalled how for a resonator structure it is possible to get negative values of the effective permeability and it is shown how this can be exploited for shielding applications. Simulation results are obtained via a commercial finite-element code through a 3-D frequency analysis. The shielding effectiveness is estimated at different operating conditions by varying the resonance frequencies of the shield, while maintaining the constant field operating frequency. Possible advantages and critical aspects of such an approach are discussed throughout this paper, and an estimation of the thrust force acting on the projectile is also provided.