Progress in Superconductivity and Cryogenics (한국초전도ㆍ저온공학회논문지)

The Korean Society of Superconductivity and Cryogenics (한국초전도저온학회)
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Effects of surface-roughness and -oxidation of REBCO conductor on turn-to-turn contact resistance

  • Y.S., Chae (Department of Electrical Engineering, Jeju National University) ;
  • H.M., Kim (Department of Electrical Engineering, Jeju National University) ;
  • Y.S., Yoon (Department of Electrical Engineering, Shin Ansan University) ;
  • T.W., Kim (Material Technology Center, Korea Testing Laboratory) ;
  • J.H., Kim (Electric Energy Research Center, Jeju National University) ;
  • S.H., Lee (Electric Energy Research Center, Jeju National University)
  • Received : 2022.11.01
  • Accepted : 2022.12.16
  • Published : 2022.12.31
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Abstract

The electrical/thermal stabilities and magnetic field controllability of a no-insulation (NI) high-temperature superconducting magnet are characterized by contact resistance between turn-to-turn layers, and the contact resistance characteristics are determined by properties of conductor surface and winding tension. In order to accurately predict the electromagnetic characteristics of the NI coil in a design stage, it is necessary to control the contact resistance characteristics within the design target parameters. In this paper, the contact resistance and critical current characteristics of a rare-earth barium copper oxide (REBCO) conductor were measured to analyze the effects of surface treatment conditions (roughness and oxidation level) of the copper stabilizer layer in REBCO conductor. The test samples with different surface roughness and oxidation levels were fabricated and conductor surface analysis was performed using scanning electron microscope, alpha step surface profiler and energy dispersive X-ray spectroscopy. Moreover, the contact resistance and critical current characteristics of the samples were measured using the four-terminal method in a liquid nitrogen impregnated cooling environment. Compared with as-received REBCO conductor sample, the contact resistance values of the REBCO conductors, which were post-treated by the scratch and oxidation of the surface of the copper stabilizer layer, tended to increase, and the critical current values were decreased under certain roughness and oxidation conditions.

Keywords

Acknowledgement

This research was supported by National R&D Programs through the National Research Foundation of Korea (NRF) funded by Ministry of Science and ICT. (Nos. 2021R1C1C2003235 and 2022M3I9A1072846)

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