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Normal transition and stability characteristics of YBCO coated conductors under AC / pulse operation

交流/脉冲操作下 YBCO 涂层导体的正常过渡和稳定性特性

基本信息

批准号：
16360136
负责人：
AMEMIYA Naoyuki
金额：
$ 9.6万
依托单位：
Yokohama National University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16360136/
关键词：
Superconductor Yttrium YBCO Eddy Current Quench Stability Alternating Current Power Application

项目摘要

S/N transition processes of monofilament / multifilament YBCO conductors as well as parallel conductors were studied experimentally and numerically, and the following results were obtained.1)Ramp-up currents and AC over-currents were supplied to single YBCO conductors to study their S/N transition processes. It was found that the time-derivative of the supplied currents does not influence the S/N transition processes of single YBCO conductors. In case of AC over-current tests, a normal zone generated near the peak of the supplied current disappeared when the magnitude of the current decreased.2)Two YBCO coated conductors were connected in parallel, and ramp-up currents were supplied to study their current sharing characteristics. Due to different contact resistances to the current lead, some current imbalance was observed in currents of two conductors. When the current of the conductor carrying more current became larger than its critical current, a normal zone was produced, and the current transferred to other conductor to influence their stability property.3)S/N transition processes of monofilament / multifilament YBCO conductors were studied numerically by the combination of the electromagnetic field analysis and thermal analysis using FEM. It was found that the externally applied AC/pulse magnetic field substantially influences the current distribution on YBCO conductors but not substantially influences the temperature distribution and quench characteristics. Longitudinal distributions of critical currents do not substantially influence quench characteristics.

通过实验和数值模拟研究了单/多丝YBCO导体以及平行导体的S/N转变过程，得到了以下结果：1）对单根YBCO导体施加斜坡电流和交流过电流，研究其S/N转变过程。结果表明，外加电流的时间导数不影响YBCO单晶的S/N转变过程。在交流过电流试验中，当电流幅值减小时，在电流峰值附近产生的正常区消失。2）将两个YBCO涂层导体并联，施加斜升电流，研究其均流特性。由于与电流引线的接触电阻不同，在两个导体的电流中观察到一些电流不平衡。当载流较大的导体的电流大于其临界电流时，会产生一个正常区，并将电流转移到其他导体上，影响其稳定性。3）采用有限元法，将电磁场分析和热分析相结合，对单/复丝YBCO导体的S/N转变过程进行了数值研究。结果表明，外加交流/脉冲磁场对YBCO超导体的电流分布有显著影响，但对超导体的温度分布和失超特性无显著影响。临界电流的纵向分布对失超特性无显著影响。