Magnetic evaluation of HTS magnetic shielding cylinders using anHTS dc-SQUID

摘要

For practical applications, an ideal magnetic shielded vessel can be realized by making use of a high-critical temperature superconductor (HTS). Generally, the value of the maximum shielded magnetic flux density Bs is used to evaluate the magnetic shielding effect of the HTS vessel. Little is known, however, of the characteristics and evaluation procedures used to determine the behavior of the magnetic flux density Bin within the shielded vessel when exposed to an external magnetic flux density Bex of less than the value of Bs. In order to evaluate the behavior of the magnetic field within the Bi-Pb-Sr-Ca-Cu-O cylinder to an applied Bex the temporal change of Bin, and the magnetic noise power spectrum (NPS) of Bin are measured by an HTS dc-SQUID magnetometer and spectrum analyzer. The present paper examines the optimum shielding conditions for constructing an ideal magnetic shielding vessel