The precise characterization of critical current, Ic is fundamental for the design and stable operation of large-scale high-temperature superconducting (HTS) applications, such as fusion magnets and power cables. However, unlike low-temperature superconductors (LTS), HTS materials exhibit complex voltage-current characteristics governed by thermal fluctuations and flux creep, leading to significant measurement uncertainties. This paper provides a comprehensive review of the international standards for Ic measurement, specifically the IEC 61788 series, with a particular focus on the transition from Nb-based conductors to REBCO coated conductors (IEC 61788-26). The theoretical background of the E-J power law model is analyzed and various definition criteria of critical current are evaluated to highlight the engineering implications of criterion dependency. Furthermore, key technical requirements for reproducible data, such as atmospheric pressure correction and current transfer length, are discussed in detail. Finally, this paper addresses the engineering gap between standardized short-sample tests and actual magnet performance, examining critical issues including screening currents, self-field effects, and mechanical stress in large-scale systems.
목차
Abstract 1. 서론 2. 임계전류의 이론적 배경과 결정 기준 2.1. 임계전류의 물리학적 배경과 공학적 정의 2.2. E-J Power Law 모델 2.3. 임계전류 결정 기준 3. 국제 측정 표준: IEC 61788과 초전도 선재의 임계전류 측정 3.1. 측정 기술의 기초: LTS 선재 표준 3.2. IEC 61788-3: Bi-2212 및 Bi-2223 선재의 임계전류 측정 [25] 3.3. IEC 61788-26: REBCO 선재의 임계전류 측정 [26] 3.4. 기계적 특성 표준과의 연계: 전기-기계적 거동 4. 고온초전도 코일에서의 임계전류 측정 이슈 및 고려사항 5. 결론 ACKNOWLEDGMENT REFERENCES
Jiho Lee [ School of Electrical and Electronics Engineering, Pusan National University/Robotics Institute of Non-Destructive Inspection, Pusan National University, Busan, Korea ]
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