Homogeneous Current Distribution in Multi-laminated HTS Tape Conductor for Pancake Coil of SMES

A multi-laminated HTS tape conductor has been recently developed to fabricate large pancake coils such as SMES. If the HTS tapes are simply laminated to form the conductor, the current distribution in the laminated tape conductor of the coil is unbalanced because of different inductances of all tapes. The pancake coil has been widely used for large magnet, because the pancake coil is tightly wound and endures large electromagnetic force. The tape transpositions at both ends of the pancake coil are effective for the coil fabrication, because it cannot damage the conductor. It is very important to analyze current distribution in the multi-laminated tape conductor used for the pancake coil. In this paper, we analyze the current distribution in the tape conductor by using circuit model, and then propose a relationship between the laminated tape number of the conductor and the pancake coil number to obtain the homogeneous current distribution. We fabricated the double pancake coil based on the relation, tested it to verify the relation and demonstrated the homogeneous current distribution in the conductor.