Proposal of Magnetic Circuit using Magnetic Shielding with Bulk-Type High T_c Superconductors —Evaluation of Magnetic Circuit using Toroidal Core—

Recently, bulk-type high T_c having a characteristic of critical current density over 10⁴ A/cm² in liquid nitrogen temperature (77K) on 1T, can be produced. They are promising for many practical applications such as a magnetic bearing, a magnetic levitation, a flywheel, a magnetic shielding and others. In this research, we propose a magnetic circuit that is able to use for the magnetic shield of plural superconductors as an application of bulk-type high T_c superconductors. It is a closed magnetic circuit by means of a toroidal core. Characteristics of the magnetic circuit surrounded with superconductors are evaluated and the possibility is examined. As the magnetic circuit of the ferrite core is surrounded with superconductors, the magnetic flux is shielded even if it leaked from the ferrite core.