Axisymmetric Simulation of Inductive Measurement Method for Critical Current Density in Bulk HTS: Relation Between Third Harmonic Voltage and Coil Current

The inductive measurement method for the critical current density in a bulk high-temperature superconductor (HTS) has been investigated by using the axisymmetric simulation. In the method, an ac current <i>I</i> ₀ sin 2pi <i>ft</i> is applied in a small coil placed just above a bulk HTS and, simultaneously, the third harmonic voltage <i>V</i> ₃sin(6pi <i>ft</i> + thetas₃) is measured. In order to simulate the inductive method, <i>I</i> ₀ - <i>V</i> ₃ curves are determined by use of the simulation and, subsequently, the critical current density is estimated. The results of computations show that the accuracy of the inductive method is influenced by neither the frequency nor the applied dc magnetic field.