Investigation of Current Distribution in Multi-Tape HTS Samples

AbstractOne of the main problems in multi-element superconductors is to ensure the current distribution between several elements in accordance with their individual critical currents.The experimental investigation of self-field current redistribution between several HTS tapes was performed in order to support the design of a resistive type SFCL. The critical currents at 1μV/cm of 12mm wide tapes SF12100 produced by Super Power were in the range 210-300A at 78K temperature. The rated rms current of SFCL project is 900 A.The samples were wound onto about 200mm diameter bobbin and consisted of one or two layers of 3 or 6 connected in parallel HTS tapes. The multi-tape conductor turns were at first charged with DC or AC (50Hz) individually. Then they were mounted coaxially and connected in opposite in order to reduce self-field and inductance values. The dynamic behavior of currents in the tapes was reconstructed from simultaneously measured data of 7 Hall probes and V-A curves of several tapes.In spite the critical currents of individual tapes were far from being equal the total critical current of the samples was close to the sum of tapes critical currents (about 750 A for 3 tapes and 1350 A for 6 tapes). Some recommendations for the improvement of current distribution uniformity are given for the case of SFCL