Shielding of AC Magnetic Fields by Coils and Sheets of Superconducting Tapes

Magnetic field shielding properties of coils and sheets of silver sheathed (Bi,Pb)
₂
Sr
₂
Ca
₂
Cu
₃
O
_10+x
tapes (1G superconductor tapes) and YBa
₂
Cu
₃
O
₇
coated conductors (2G superconductor tapes) are reported. Shielding properties were measured at 77 K, with varying field amplitude and frequency of external magnetic field, using Hall probes and a phase sensitive technique. Shielding factor data on several coils and sheets are presented as a function of external field amplitude and frequency. Magnetic field shielding of up to 50% was observed at field amplitudes of < 10 mT. Differences in frequency dependence of shielding properties of test shields fabricated from 1G and 2G conductors are discussed.