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Description
A new facility for the measurement of AC loss in superconductors at high dB/dt has been developed, and recently tested and calibrated for operation. The test device has a spinning rotor consisting of permanent magnets arranged in a Halbach array; which exposes samples in a stator position with a peak radial field of 0.57 T, and with high rotation speeds up to 3600 rpm achieves a radial dB/dt is 543 T/s and tangential dB/dt is 249 T/s. Loss is measured by calorimetry using nitrogen boiloff from a double wall calorimeter feeding a gas flow meter, and the system was calibrated using power from a known resistor. For calibration, Cu-tape and YBCO-tape losses were measured and compared to results of a solenoidal magnet AC loss system measurement of the same samples but limited to a field of amplitude 0.1 T and a dB/dt of 100 T/s. Herein the use of this system for measuring AC losses of a variety of YBCO coated conductors and cables will be performed, and results will be compared to measurements with a a solenoid magnet system and theory. Coated conductors are provided by several manufacturers with different architectures including filamented, varying width, and different quench protection metal layers with varying thickness. Also AC losses will be reported on several types of cable structures, including stacked tapes and conductor-on-round-core (CORC) structures.
Acknowledgement: Air Force Office of Scientific Research (AFOSR), U.S. Air Force ResearchLaboratory – Aerospace Systems Directorate (AFRL/RQ)