An electromagnet with inductive superconducting shielding

Following the suggestions of the companion paper, an electromagnet with a suitably shaped superconducting shield was investigated. As expected it was found that the gap field can be reliably computed and is highly homogeneous. With pure soft superconducting material, the magnet performance is reversible up to the critical field; beyond that a particular shaped boundary between normal and superconducting states may form, and the boundary advances, with delay, into the material as a result of ordinary skin effect. In hard superconductors, hysteresis like frozen flux effects are observed, from which the critical current density can be determined. © 1969.