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ST509 - Through-wall Excitation of a Magnet Coil by an External-rotor HTS Flux Pump

Through-wall Excitation of a Magnet Coil by an External-rotor HTS Flux Pump


Chris W. Bumby1, Andres E. Pantoja1, Hae-Jin Sung2, Zhenan Jiang1, Ravi Kulkarni3, and Rodney A. Badcock1

1The Robinson Research Institute, Victoria University of Wellington, New Zealand
2The Department of Electrical Engineering, Changwon National University, Changwon, Republic of Korea
3The School of Engineering, Auckland University of Technology, Auckland, New Zealand
 
Abstract — High Temperature Superconducting (HTS) magnet systems conventionally require normal-conducting current leads, which connect between the HTS circuit and an external power supply located at room temperature. These current leads form a thermal bridge across the cryostat wall, and they represent the dominant heat load for many magnet applications. Superconducting flux pump devices are an alternative approach to the excitation of a magnet coil which can eradicate this parasitic heat load, as such devices do not require direct physical connection to the HTS circuit. However, previously proposed flux pump designs have required power-dissipating active components to be located within the cryogenic envelope, thus imposing their own parasitic heat load.
Here we report the successful demonstration of a mechanically-rotating HTS flux pump which operates entirely outside of the cryogenic envelope. This prototype device projects flux across a cryostat wall, leading to the injection of DC current into a thermally-isolated closed HTS circuit. This is achieved through the implementation of a flux-concentrating magnetic circuit employing ferromagnetic yoke pieces, which enables flux penetration of the HTS circuit at large flux gaps. We have demonstrated the injection of DC currents of > 30 A into a closed HTS circuit whilst operating this device across a cryostat wall
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Keywords (Index Terms) — Flux pump, HTS dynamo, coated conductor, current leads, YBCO, superconducting generator.
 
IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), April 2016. 
Received November 17, 2015; Selected December 3, 2015. Reference No. ST509; Category 6. 
MT-24 preprint 2PoCF_11The final paper version was published online in IEEE Trans. Appl. Supercond. (IEEE Xplore) DOI: 10.1109/TASC.2016.252660, June 2016.