The measurement of transport current density is significant for investigations on improving the properties of REBa₂Cu₃O_7−x (REBCO, where RE refers to rare-earth elements)-coated conductors (CCs). In this work, a protocol for mapping the transport current density of CC by magneto-optical imaging (MOI) is presented. A calibration method is developed based on the non-linear physical governing function for the MOI indicator, in which only two parameters are determined, i.e. the anisotropic magnetic field B_A , and cM_s , which is the multiplication of the constant c related to the thickness of the MOI indicator and the spontaneous magnetization M_s . The experimental results also showed that they were independent of the optical measure condition but dependent on temperature, making this calibration method comparative among different utilizers. The numerical results clearly manifested that the selected window size of the magnetic field around a long superconducting tape is closely related to the error of the reconstructed current density. A large window size of the magnetic field is needed to precisely reconstruct the transport current density. For actual MOI testing, a practical approach to extend the magnetic field data outside the MOI window was realized by fitting with a power function according to Ampere’s law, through which the false current density outside the sample is automatically suppressed to a large extent. On this basis, the mapping of the transport current density in the CC sample was achieved. It is believed that this work will improve MOI for a more precise measurement of the transport current density for long superconducting strips.

中文翻译：

---

通过磁光成像绘制 REBCO 涂层导体传输电流密度的协议

输运电流密度的测量对于改善材料性能的研究具有重要意义关于Ba ₂ Cu ₃ O _7−X （关于BCO，哪里关于指稀土元素）涂层导体（CC）。在这项工作中，提出了一种通过磁光成像 (MOI) 绘制 CC 传输电流密度的协议。提出了一种基于惯性矩指示器非线性物理控制函数的标定方法，其中仅确定两个参数，即各向异性磁场巴_{_} ， 和厘米_级 ，这是常数的乘法C与 MOI 指示器的厚度和自发磁化强度有关多发性_硬化症 。实验结果还表明，它们与光学测量条件无关，但取决于温度，使得该校准方法在不同用户之间具有可比性。数值结果清楚地表明，长超导带周围磁场的选定窗口尺寸与重建电流密度的误差密切相关。需要大的磁场窗口尺寸来精确重建传输电流密度。对于实际的MOI测试，通过根据安培定律拟合幂函数，实现了将磁场数据扩展到MOI窗口之外的实用方法，从而在很大程度上自动抑制了样品外部的虚假电流密度。在此基础上，绘制了CC样品中的传输电流密度图。人们相信，这项工作将提高 MOI，从而更精确地测量长超导带的传输电流密度。