基于闭合超导线圈组的磁场屏蔽系统研究

Magnetic shielding provides general protection for precision measuring apparatus. To enrich the family member of magnetic shielding, we propose a novel magnetic shielding system based on closed high temperature superconductor(HTS) coils. The capability of the system is based on the principle that a closed loop can resist flux variation and keep the flux constant inside. More important thing is that the ratio of the radius and the turn number between the coils have to satisfy a number of conditions, with which arbitary cancellation ratio can be reached. The advantage of the system is that first, it is open-type with which the protected target can communicate with outsides optically or wirelessly; secondly, it automatically resists magnetic field without using any electronic devices and thus has good property in mobility and compatibility; third, the system has a broad frequency spectrum, in particularly at low frequency. The initial testing shows that the shielding ability of the system at 0.1-200 Hz, the spectrum caused by 50Hz power line or electrical devices does not show evident decay at this spectrum. In this project, we are going to study the design theory of the system, eletromagnetic characteristic of the system and construction technique of the system in a parallel way. More specifically first, build the inverse magnetic field theory and robust design theory for the shielding system; second, study the frequency spectrum of system and explain the property based on flux motion theory of the HTS； third, study the construction technique of the system and build a shielding system for Magnetocardiography (MCG) measurement, which will be used in a hospital for human being testing. The system can resist magnetic noises in a scale of 40dB.

磁场屏蔽是许多精密测量科学的通用保障性技术。为了丰富磁屏蔽家族的成员，弥补传统屏蔽系统的局限性，项目提出了一种基于闭合超导线圈组的磁场屏蔽系统。它通过主动调控线圈之间的半径比和匝数比，可实现任意比例感应抵消外界噪音磁场。这种屏蔽系统具有以下优点：第一，光学透明，被保护物体可与外界进行光学和无线通讯。第二，自动抵消磁场，无需辅助电子设备；第三，低频区屏蔽能力不衰减，经初步测试，在0.1-200Hz范围，即因输电线和用电器产生噪音磁场的主要频域，系统屏蔽能力一致。 本项目拟对该新型屏蔽系统设计理论、电磁特性和工程实现方法开展研究，具体研究内容和目标包括：第一，建立屏蔽系统电磁场逆问题及鲁棒性设计理论；第二，研究屏蔽系统频谱，幅域特性，并从高温超导磁通穿透的微观过程阐述机理；第三，探索屏蔽系统的工艺实现方法，搭建一套配合心磁测量的屏蔽系统，可屏蔽噪音磁场40dB以上，在三甲医院环境开展人体测试。

本基金面上项目51477088《基于闭合超导线圈组的磁场屏蔽系统研究》各项研究内容与研究目标均达到了项目申请阶段制定的目标。具体而言，项目组提出了一种全新的基于超导线圈组的Tesla-Shielding(TS)开放式噪音磁场屏蔽技术，建立屏蔽系统电磁设计理论，建立了精细化的有限元电磁仿真模型；摸索了非金属杜瓦制造工艺与低阻超导接头焊接工艺；设计并实现了3种规格的原型样机，完成样机屏蔽效能测试，证实在0.1-10000Hz频谱区间可实现50dB以上的屏蔽效能。本项目最重要的成果是项目组与航空航天大学原子磁强计研究组，航空材料无损检测研究组，北京大学，解放军309医院心磁测试研究组，河北科技大学生物磁效应研究组，北京布润科技有限公司脑电研究组开展了大量的应用合作研究。联合测试显示了新型磁场屏蔽系统的优越性与生命力，为未来大规模应用推广打下基础。项目组后续提出了一种全频段开放式磁场屏蔽系统概念，获得自然基金面上项目51877119滚动支持。项目总计发表SCI文章7篇，其中一篇发表在应用物理知名期刊，Applied Physics Letter杂志，另有3片在投状态。项目总计申请授权专利3项，其中授权美国专利1项，培养硕士博士研究生2人。