Numerical Investigation on Applicability of jC-Measurement Method to Multiple High-Temperature Superconducting Tape

A numerical code has been developed in order to investigate the applicability of the permanent magnet method to vertically-stacked multiple high-temperature superconducting (HTS) tapes. The permanent magnet method was proposed to simply and contactlessly measure the critical current density in the HTS tape. By this method, the critical current density is estimated from the proportional relation between the critical current density and the Lorentz force working on the permanent magnet. The Maxwell equation, coupled with the superconductivity characteristics, is solved by the edge-based finite element method to investigate the effect of the number of HTS tapes on the Lorentz force. As a result, it is clear that the permanent magnet method can be applied to measurement of the critical current density in the multiple HTS tapes although there is an upper limit of the number of HTS tapes in which the critical current density can be measured. In addition, by using stronger magnet, the permanent magnet method can measure the critical current density when more number of HTS tapes are stacked