AC Loss Measurement of Double Pancakes Wound With MgB2 Rutherford Type Superconductor

Double pancakes (DPs) for a Superconducting Magnetic Energy Storage (SMES) coil have been developed using MgB ₂ Rutherford type superconductors. The DPs with 400 mm ID and about 600 mm OD were wound with Rutherford type conductors cabled by twisting multi-filamentary MgB ₂ strands. For use in an indirect cooling system, the DPs and thin pure copper sheets as thermal conductors were alternately stacked, and the SMES coil was assembled. In the experiment, while continuous triangular current waveforms up to 600 A and DC current were supplied to two configurations of the SEMS coil, the AC loss at 4.2 K was measured by calorimetric method. By comparing the losses under each excitation and configuration, the AC loss in the SMES coil and an eddy current loss in the copper sheets were obtained, separately. The resultant AC loss in the SMES coil was in agreement with the theoretical values.