Plasma and Fusion Research

Volume 16, 2405007 (2021)

Regular Articles

Study of an Air-Core High Temperature Superconducting Current Transformer for Large Current Supply
Hokuto YAMADA, Nozomu NANATO1), Keisuke SHIRAI and Tetsuhiro OBANA2)
Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan
National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan
(Received 12 November 2020 / Accepted 8 December 2020 / Published 5 March 2021)


Large AC current supply is essential for measuring the current transport characteristics of superconducting wires, such as AC loss in helical coil conductors. Commercial current supplies are generally too large and heavy, and therefore, they are inconvenient to use with the superconducting wires. The authors have been studying a small and lightweight large current supply with a high temperature superconducting (HTS) current transformer. An air-core HTS current transformer is suitable for the miniaturization of AC supply because this transformer does not have an iron core and thus does not have large volume and heavy weight. In this paper, we report that the current supply with the air-core HTS current transformer can output large current with high frequency by using the resonance phenomenon. Furthermore, we provide a method for the detection of normal transitions in the transformer by measuring the current transformation ratio of its primary and secondary currents. This detection method is composed of a simple measurement system, and experimental results show the usefulness of this detection method for the air-core transformer.


air-core transformer, HTS transformer, current supply, resonant phenomenon, normal transition

DOI: 10.1585/pfr.16.2405007


  • [1] Y. Narushima et al., Plasma Fusion Res. 5, 1405076 (2020).
  • [2] N. Nanato, T. Adachi and T. Yamanishi, J. Phys.: Conf. Series 1293, 012072 (2019).
  • [3] N. Nanato, S. Tanaka and S. Tenkumo, J. Phys.: Conf. Series 1054, 012070 (2018).
  • [4] N. Nanato, N. Kishi, Y. Tanaka and M. Kondo, J. Phys.: Conf. Series 871, 012101 (2017).
  • [5] K. Wakasugi et al., Physica C 357, 1209 (2001).
  • [6] M. Kondo et al., Abstracts of the 31st International Symposium on Superconductivity, APP4-5 (2018).
  • [7] K. Fujiki, M. Ishihara, K. Umetani and E. Hiraki, Proc. Eur. Conf. Power Electron. Appl., pp. 1-9 (2019).
  • [8] M.N. Wilson, Superconducting Magnets (Oxford University Press, 1983) pp. 200-232.
  • [9] Y. Iwasa, Case Studies in Superconducting Magnets, Design and Operation Issues, 2nd ed. (Springer Science, 2009) pp. 467-544.
  • [10] N. Nanato, W. Asai and S. Murase, Physics Procedia 27, 416 (2012).
  • [11] Y. Iwasa, Case Studies in Superconducting Magnets, Design and Operation Issues, 2nd ed. (Springer Science, 2009) pp. 468-470.