Measurement of AC Current Distributions in Three HTS Tapes Arranged in Parallel

We have developed a measurement method to evaluate the current distributions in several HTS tapes arranged in parallel. In this method, the current distributions are indirectly found from the results of the field distributions measured by a pickup coil located around the upper surface of the sample tapes. To confirm the accuracy and sensitivity of this method, current distributions in a test conductor made of three copper tapes are measured. Numerical and measured current distributions are compared, and it is found that our method is accurate enough to measure the current distributions in HTS tapes. Using this method, we measured the current distributions in Bi-2223 tapes arranged in parallel at room temperature and 77 K. The comparison between the experimental and numerical results shows a good agreement. On the basis of the obtained results, the characteristics of the AC current distributions in the HTS tapes are discussed.