Comparative Study of Magnetic Characteristics of Air-Core and Iron-Core High-Temperature Superconducting Quadrupole Magnets

Jeyull Lee, Junseong Kim, Geonwoo Baek, Yojong Choi, Yoon Hyuck Choi, Zhan Zhang, Yoon Do Chung, Hyoungku Kang, Haigun Lee, Sangjin Lee, Tae Kuk Ko

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


High-temperature superconductors (HTSs) have a much larger thermal margin than low-temperature superconductors, owing to their high critical temperatures. This characteristic allows HTS magnets to tolerate extremely high heat loads that may arise from radiation. Therefore, research on the development of HTS quadrupole magnets is progressing widely. Quadrupole magnets are commonly used for focusing the transported beams of particles in accelerators. In order to focus the beam, the quadrupole magnet uses an iron yoke with a hyperbolic contour. However, the iron yoke induces nonlinear magnetic characteristics because of saturation. Therefore, an air-core HTS quadrupole magnet is proposed to improve the magnetic characteristics. In this paper, we design air-core and iron-core HTS quadrupole magnet models using a harmonic matching method. The field gradient and effective length of both magnets are 12.1 T/m and 550 mm, respectively. In order to verify the performances of the proposed air-core quadrupole magnet, the magnetic field gradient, field uniformity, and effective length are analyzed for operating currents ranging from 50 to 400 A.

Original languageEnglish
Article number8234611
JournalIEEE Transactions on Applied Superconductivity
Issue number3
Publication statusPublished - 2018 Apr

Bibliographical note

Funding Information:
Manuscript received August 29, 2017; accepted December 11, 2017. Date of publication December 22, 2017; date of current version January 9, 2018. This work was supported in part by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP), in part by the “Human Resources Program in Energy Technology” of the Korea Institute of Energy Technology Evaluation and Planning, and in part by the Ministry of Trade, Industry & Energy, Republic of Korea (Nos. 2017R1A2B3012208 and 20164030201100). (All authors contributed equally to this work.) (Corresponding author: Tae Kuk Ko.) J. Lee, J. Kim, G. Baek, Y. Choi, and T. K. Ko are with the Department of Electronics and Electrical Engineering, Yonsei University, Seoul 03722, South Korea (e-mail:

Publisher Copyright:
© 2017 IEEE.


  • Air-core quadrupole magnet
  • effective length
  • evolution strategy
  • field gradient
  • field uniformity

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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