Abstract: An inner circumferential portion is formed by winding one of first and second superconducting wires each having a band shape. An outer circumferential portion is formed by winding the other of the first and second superconducting wires around the inner circumferential portion. A welding portion joins the first and second superconducting wires to each other by welding between the inner circumferential portion and the outer circumferential portion. The first superconducting wire is higher in strength than the second superconducting wire. The second superconducting wire is smaller in thickness than the first superconducting wire.

Abstract: An inner circumferential portion is formed by winding one of first and second superconducting wires each having a band shape. An outer circumferential portion is formed by winding the other of the first and second superconducting wires around the inner circumferential portion. A welding portion joins the first and second superconducting wires to each other by welding between the inner circumferential portion and the outer circumferential portion. The first superconducting wire is higher in strength than the second superconducting wire. The second superconducting wire is smaller in thickness than the first superconducting wire.

Abstract: A method of measuring the critical current value of a superconducting wire comprises the step of measuring first to mth (m denotes an integer of at least 2) current values (I1, I2, . . . , Im) and first to mth voltage values (V1, V2, . . . , Vm) corresponding to the respective ones of the first to mth current values. The first current value I1 and the first voltage value V1 are measured by retaining the current fed from a constant current source to the superconducting wire in a state set to a first set value I1a for a constant time and thereafter measuring the current flowing through the superconducting wire and a voltage generated in the superconducting wire.