Numerical investigations on relation between critical current density and third harmonic voltage in HTS

The inductive method for measuring the critical current density is investigated by using the numerical simulation. When the high-temperature superconductor is exposed to the magnetic field generated by the ac coil current, the voltage induced in the coil contains not only a linear component but higher harmonics. The harmonic voltages are numerically calculated as a function of the coil current. The results of computations show that, above a certain limit of the coil current, the third harmonic voltage is suddenly excited. In addition, it is also found that the square root of the third harmonic voltage is approximately a linear function of the coil current.