Critical Current and Its Magnetic Field Effect Measurement of HTS Tapes Forming DC Superconducting Cable

We constructed a test stand of 20 m-class DC superconducting power transmission cable in Chubu University, in 2006. The cable consisted of thirty-nine Bi-2223 HTS tapes in two layers; nineteen tapes were used in the first layer and twenty tapes were used in the second layer. One of the features of the cable is that each HTS tape in the first layer is electrically isolated. Therefore, we can apply the current to the individual HTS tapes in the first layer. We measured critical current of the one HTS tape in the first layer when current was applied to the other HTS tapes, and compared the result with the magnetic field calculation due to the applied current. The critical current increased by 2 similar to 4% when the current was applied to all other eighteen HTS tapes in the same layer. From the magnetic field calculation, we concluded that the self magnetic field of the measured HTS tape was eliminated at the tape edge by the applied magnetic field from the neighbor HTS tapes, and then the critical current increased.