单边核磁共振传感器研究及其应用
收稿日期: 2015-03-06
修回日期: 2016-01-21
网络出版日期: 2016-03-05
基金资助
国家自然科学基金资助项目(51107150,51377182).
A Single-Sided NMR Sensor: Design and Applications
Received date: 2015-03-06
Revised date: 2016-01-21
Online published: 2016-03-05
单边核磁共振(single-sided NMR)传感器具有体积小、造价低和结构开放等特点,特别适用于大型样品的现场无损检测,具有广阔的应用前景.该文介绍了一种均匀度较高的单边核磁共振传感器,在10 mm×10 mm的水平目标区域内,静态磁场均匀度为338×10-6,在垂直方向上静态磁场具有4.6 T/m的恒定梯度.结合该磁场分布的梯度特性,提出了一种基于快速傅里叶变换和带通滤波处理的回波信号处理方法,可提取薄层样品的核磁共振信号,从而实现对样品纵深方向的高分辨率一维测量(分辨率达到50 μm).最后使用该传感器对复合绝缘子高分子聚合物、液体的扩散行为,以及植物叶片的枯萎过程进行了测量.展现了该方法在高分子材料分析、液体测量以及农业应用方面的潜力.
关键词： 单边核磁共振(single-sided NMR); 磁体设计; 扩散系数; 复合绝缘子
籍勇亮 , 崔现军 , 候兴哲 , 吴高林 , 王谦 , 李龙 , 徐征 . 单边核磁共振传感器研究及其应用[J]. 波谱学杂志, 2016 , 33(1) : 66 -76 . DOI: 10.11938/cjmr20160106
Single-sided NMR sensors are especially suitable for nondestructive examination of large samples, due to their features such as small size, low cost, and open structure. This paper presents the design and applications of a single-sided NMR sensor with relatively high field uniformity. The uniformity of B0 was estimated to be 338×10-6 in an area of 10 mm×10 mm in the horizontal direction; while there was a constant gradient of 4.6 T/min the vertical direction. According to the distribution of the magnetic field gradient, a signal processing method based on FFT and band-pass filter was proposed to extract NMR signals from a thin layer of the samples. The one-dimensional resolution in the depth direction was about 50 μm. Application experiments are presented, including assessing the aging status of polymer composite insulator, measuring the diffusion coefficient of liquids, and analyzing the withering process of plant leaves. It is concluded that the single-sided NMR sensor developed may have potential applications in many fields.
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