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Description
Reducing AC loss in high-temperature superconducting (HTS) coils is critical in HTS applications such as SMES (superconducting magnetic energy storage) and fast ramping magnets. One effective approach is applying magnetic flux diverters to reshape the magnetic field distribution in the vicinity of end coils/windings. However, the benefits of MFDs diminish in high magnetic fields that exceed the saturation field of the MFDs. Alternatively, superconducting shielding coils (SSC) present a promising solution due to their high-field diamagnetic properties. Nevertheless, there is no experimental benchmark on the AC loss reduction achieved by SSC.
In this work, AC loss in an HTS coil assembly with and without SSC is measured at 77 K. The coil assembly consists of three double pancake coils (120 turns in total). The coils assembly and SSC are respectively wound from 4-mm-wide SuperPower and 12-mm-wide THEVA wires. The experimental results were compared with the finite element modelling results based on the T-A formulation. The AC loss reduction at different operating currents and frequencies achieved by SSC is analysed.
Keywords: HTS coil, AC loss reduction, superconducting shielding coils, T-A formulation
Acknowledgement:
This work was supported by the U.S. Office of Naval Research under the "Fast-Ramping Superconducting Magnets" grant with awarded No. N629092412037, in part by the Air Force Office of Scientific Research under award number FA2386-22-1-4054, and in part by the New Zealand Ministry of Business, Innovation, and Employment under the Advanced Energy Technology Platform program “High power electric motors for large scale transport” contract number RTVU2004.
