Evaluation of Joint Resistance of YBCO Single-Turn Coil

In order to develop superconducting joint technology, a field decay system was setup for the joint resistance measurement. To verify the feasibility of the testing system, a YBCO conductor joint, which was a single-turn loop coil with joint soldered by low-temperature solder, has been fabricated and used as the sample. The testing results have been compared with that by the standard four-probe method. The resistance measured by the four-probe method is 5.75x10−8Ω, and using this system, the performance of the joint is 4x10−8 Ω. The measured resistance by field decay method is less than that by the four-probe method. This is mainly due to the self-inductance of the YBCO closed coil based on FEM is smaller than the actual value.