Patent ID: 8788227

Claim:
A method for measuring critical current density of superconductor wires, the method comprising: (a) applying an external magnetic field to the superconductor wires; (b) measuring a magnetization loss of the superconductor wires, according to the application of the external magnetic field; (c) normalizing the measured magnetization loss, and then calculating a full-penetration magnetic field of the superconductor wires according to the normalized magnetization loss; and (d) calculating a critical current density of the superconductor wires according to the calculated full-penetration magnetic field, wherein: at (b), a Brandt's strip model equation Q m = 2 ⁢ ⁢ B m 2 ⁢ μ 0 ⁢ π ⁢ ⁢ ω 2 ⁢ ⁢ β ⁢ ⁢ d ⁡ [ 2 β ⁢ ln ⁢ ⁢ ( cosh ⁢ ⁢ β ) - tan ⁢ h ⁢ ⁢ β ] is applied to the calculation for measuring the magnetization loss of the superconductor wires, where Q m is the magnetization loss by the external magnetic field applied in a vertical direction of the superconductor wires, B m is a dimension for the external magnetic field, ω is a frequency, β is a ratio of the external magnetic field to a characteristic magnetic field, μ 0 is a vacuum permeability which is a constant value, and d is the width of the superconductor wires; and further wherein operation (c) comprises: (c1) normalizing the measured magnetization loss; (c2) differentiating the normalized magnetization loss; and (c3) calculating the full-penetration magnetic field by determining a relation of the characteristic magnetic field applied to Brandt's strip model equation and the full-penetration magnetic field, according to a differentiated value of the normalized magnetization loss, and further wherein at (c3), the relation of the characteristic magnetic field and the full-penetration magnetic field is expressed as an equation B d =β×B p , where B d is the characteristic magnetic field, B p is the full-penetration magnetic field, and β is the ratio of the external magnetic field to the characteristic magnetic field; and further wherein β is determined when the differentiated value of the normalized magnetization loss becomes zero at (c2).