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

Abstract

Magnetic field shielding properties of coils and sheets of silver sheathed (Bi,Pb) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Sr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Ca <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10+x</sub> tapes (1G superconductor tapes) and YBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> 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.