REBCO超导眼型结构永磁体励磁机理及结构设计研究

With the development of second generation high temperature superconducting materials, fundamental studies on superconducting permanent magnets such as superconducting bulks and stack tapes are relatively mature. While due to the restrictions of fabrication techniques, the size of these superconducting magnets is still far away from the practical requirement of industrial applications. This project will introduce a new type of superconducting permanent magnet which can be easily fabricated in different sizes and shapes. The project will present the study on magnetization mechanism of eye-shape superconducting permanent magnet, numerical models based on classical superconducting theory, multi-physics finite element method will be built to represent the entire magnetization process, and the numerical models will be also used to explain the accumulation of trapped field during multiple pulsed magnetization. On basis of this phenomenon, optimization of magnetization technique will be carried out to achieve the maximum trapping field rate, the optimized magnetization technique will be used to obtain the ultimate trapped magnetic field of eye-shape superconducting permanent magnet under different temperatures. At the same time, two different strategies will be used to modify the asymmetry magnetic field distribution of eye-shape magnet, one is using multi-split superconducting tapes, the other is using hybrid magnet technology. Finally, this project will discuss the feasibility of using the eye-shape superconducting permanent magnets in superconducting motors and portable medical magnets. .Progress achieved in this project will systematically explain the magnetization mechanism and working characteristics of superconducting eye-shape permanent magnet, the new theory will be helpful to complete the knowledge system of superconducting permanent magnet. Optimizations of both structure and magnetization technique will improve the working performance of this new superconducting permanent magnet, and make it more practical for the industrial applications.

随着高温超导材料制备技术的发展，超导块材、堆叠带材永磁体的基础研究已经相对成熟。由于这两类技术均受限于材料的制备工艺，永磁体尺寸距离实际应用需求仍存在差距。本项目中，将重点研究一种大尺寸、易制备的超导眼型结构永磁体，项目将综合经典超导理论以及有限元仿真技术探索该类型永磁体的励磁机理，重点分析该类型永磁体在多脉冲励磁过程中出现的俘获磁场累积效应。基于磁场累积效应，综合优化出最适用于该类永磁体的励磁策略，尝试获取该类型永磁体在各温度下的极限俘获磁场值。本项目还将尝试使用多分裂超导带材、混合型磁体等策略来解决由于磁体结构不对称带来的磁偏角问题。项目最后将讨论该类型超导永磁体在超导电机、移动式医疗磁体中的应用可行性。本项目的研究成果将系统性解释新型超导永磁体的励磁机理以及运行特性，丰富超导永磁体的知识体系；从空间结构以及励磁技术上的综合优化技术将更有利于该类超导永磁体在工业界的应用推广。

超导眼型结构永磁体由多根中间分裂的超导带材组成，且每根超导带材中电流能够持续地流动，形成超导环流。因为没有接头的存在，带材自身的电阻可以忽略不计，可近似实现电流的永久闭环。且由于其制备工艺的灵活性，可高性价比的实现大尺寸超导永磁体的制备。本项目针对高温超导眼型结构永磁体的励磁机理展开系统研究，有针对性地提出了面向眼型磁体的有限元仿真方法和基于宏观电路的数值建模仿真方法，成功实现了大匝数眼型永磁体的数值模拟；通过自主设计搭建脉冲励磁平台，对眼型磁体的样品进行脉冲励磁测试，验证了仿真方法的有效性的同时探究了眼型磁体励磁特性，包括眼型磁体的基本特性，脉冲励磁策略对俘获磁场的影响，退磁过程以及不同温区下俘获磁场特性，形成一套优化的脉冲充磁策略。围绕眼型磁体存在磁偏角这一问题，提出了混合型超导永磁体这一概念，通过使用异形超导块材填充的方式，同时实现改善表面磁场的均匀度以及增强俘获磁场的目的；与此同时基于自主研发的空间磁场扫描平台，提出了针对眼型超导永磁体的表面磁场评价方法。项目执行期间，一直致力于超导眼型永磁体的推广应用，除磁共振成像以及超导电机领域，项目组尝试将超导永磁体回归本源，应用到超导磁屏蔽领域，并论证了该类型永磁体在超导限流器中的应用。.项目执行期间发表SCI论文7篇，获国家发明专利授权3项，培养硕士生4人。本项目的研究结果揭示了高温超导眼型永磁体的励磁机理，制定了相应的优化励磁策略，重点攻克了该类型永磁体由于结构而导致的磁偏角问题。在理论上为眼型高温超导永磁体走向工程应用奠定了重要的基础。