A Study on High Temperature Superconducting Coil of Different Coil Arrangements

As for the stored energy density, the solenoid coil has the larger value. On the other hand, the toroidal field coil has the least leakage flux. The primary concern of HTS SMES coil is the reduction of the cost, while securing superconducting coil performance. For this purpose, the required HTS tape length needs to be as short as possible. The critical current and n values of HTS tapes depends on the magnetic fields as well as its field angle to the tapes. Therefore, the performance of magnets wound with HTS tapes needs to be analyzed based on above factors. The current-voltage characteristics of the HTS coil were analyzed by means of fitting equations of the critical current and n value obtained from the measured values of the Bi2223/Ag tape. The stored energy of four kinds of coil arrangement was analyzed, thereby pursuing the shortest length of HTS tapes. The toroidal coil requires 58% longer HTS tapes than the solenoidal coil to store the energy of 100 kJ, but 0.01 T leakage field region at the mid-plane is about a half of the solenoid coil.