AC losses in superconductors shielded by a normal metal or another superconductor

Abstract

We investigate the flux penetration into the system of two (super-or normal conducting) regions when some of the regions are 'shielded' by the other one. The shield material may also consist of a normal conductor or superconductor. For simplicity, we consider this system in the slab geometry. The results indicate that shielding a superconducting cable by normal metal can decrease the total coupling losses. This effect surprisingly occurs already at frequencies much lower than the characteristic frequency corresponding to the maximum losses per cycle.