Study on three-dimensional flux dynamics in bulk superconductor for improving its magnetization performance

Re-BaCuO大块超导体具有良好的磁通钉扎性能，有望作为高磁通源应用。对于这样的应用，脉冲场磁化是一项重要的技术，其性能需要改进。本研究旨在研究脉冲磁场作用于具有空间非均匀超导特性的块体超导体时的磁通动态，阐明脉冲磁场作用于块体超导体时的磁通运动和感应电流分布，并考虑脉冲磁场磁化性能的改善。进行了实验和数值分析。在实验中，使用搜索线圈和霍尔探头测量了脉冲磁场磁化过程中磁通密度分布的变化以及由此产生的俘获磁通密度分布。结果明确了磁通密度分布与外加磁场的关系。用于数值分析的AXI…分析工具在液氮浸没冷却和制冷机传导冷却的冷却条件下，考虑了块体超导体的伏安特性及其临界电流密度与磁通密度和温度的关系，建立了更对称的三维电磁场和温度耦合问题。此外，还对几个案例进行了全三维分析和讨论。利用这些分析工具和模型，对不同条件下块体超导体的脉冲场磁化过程进行了数值分析。分析结果与实验结果定性地吻合，表明所建立的分析工具和模型可以对超导体中的电磁现象和温度分布进行详细的分析，从而对块体超导体在脉冲磁场磁化过程中的磁通运动和动力学进行了讨论和澄清。较少

RE-Ba-Cu-O bulk superconductor has the good flux-pinning property and is expected to be applied as a high flux source. For such an application the pulsed field magnetization is an important technique and its performance improvement is required. This study aims at examining flux dynamics during the pulsed field magnetization process, clarifying flux motion and induced current distribution when a pulse magnetic field is applied to bulk superconductor with spatially inhomogeneous superconducting properties, and considering performance improvement of pulsed field magnetization. Both experiments and numerical analysis were carried out.In the experiments search coils and a hall probe were used to measure the variation of flux density distribution during the pulsed field magnetization and the resultant trapped flux density distribution. The results have clarified the relation between the flux density distribution and the applied magnetic fields. For numerical analysis, a analysis tool for axi … More symmetric three-dimensional coupled problems of electromagnetic and temperature fields has been developed with the voltage-current characteristics of bulk superconductor and the dependence of its critical current density on magnetic flux density and temperature taken into account under the cooling conditions of immersion cooling by liquid nitrogen and conduction cooling by a cryocooler. In addition full three-dimensional analysis was also carried out and discussed for several cases. With these analysis tools and models the numerical analysis of pulsed field magnetization process of bulk superconductor were performed under the various conditions. The analysis results qualitatively agreed with experimental results, and indicate that the analysis tools and models can be used for the detailed analysis of electromagnetic phenomena and temperature distribution in the superconductor.From these experimental and analysis results the flux motion and dynamics in bulk superconductor during pulsed field magnetization has been discussed and clarified. Less