用于长城等古建筑探测的NMR探测器的磁体设计

以万里长城为代表的古建筑是世界瑰宝,更是中华民族的象征和骄傲.本文提出利用便携式核磁共振(NMR)装置来探测研究这类古建筑的建筑材料,在不对其造成损伤的基础上,发掘其隐含的科学、技术和工程相关的丰富信息.为此,作为第一步,设计了适合于探测这类古建筑的便携式单边NMR探测器组合式磁体.该探测器的磁体结构以semi-Halbach为基础,通过不同磁体模块间的组合得到对应移动探测模式、长距离探测模式和均匀磁场探测模式的磁体结构.随后根据优化结果,设计加工了磁体组件,并采用该磁体进行了流体、长城城砖和现代红砖的NMR实验,实测结果与模拟一致.该组合式磁体的优点在于通过不同磁体模块组合,实现了多种探测方式,适用于探测长城等这类古建筑物需要多种探测模式的科学研究.

Design of Magnets for in Situ NMR Detection Devices Intended for Preservation of Ancient Architectures

Ancient architectures such as the Great Wall are symbols and pride of the Chinese nation, and precious treasures of the world. Portable NMR detection devices have been proposed to examine the building materials of such ancient architectures non-invasively, and to provide information regarding the science, technology and engineering behind these architectures. In this study, the magnets for such portable NMR detection devices were designed and built, which were all based on a semi-Halbach magnet structure. On top of the basic design, different modules were added to achieve different functionality, including the magnet for mobile measurement, the magnet for high depth measurement, and the"homogeneous" field mode. The measured magnetic field (B0) distributions for these magnets agreed well with the simulated results, with only slight differences. Experiments on bricks were performed to verify the performance of these magnets.