Affiliations: [a] State Key Laboratory of Power Transmission Equipment
and System Security and New Technology, Chongqing University, Chongqing, China
Correspondence:
[*]
Corresponding author: Zheng Xu, State Key Laboratory of Power
Transmission Equipment and System Security and New Technology, Chongqing
University, Chongqing 400044, China. Tel./Fax: +86 135 2747 5882; E-mail: [email protected]
Abstract: This study presents a high-performance single-sided portable nuclear
magnetic resonance (NMR) sensor. The magnet array, which is composed of five
identical cuboid permanent magnet blocks and two passive shimming sheets,
generates a highly uniform B_{0} field in a 10
× 10 mm^{2} lateral area. Along the
two orthogonal lines in this lateral area, the measured
B_{0} strength variation is less than 338 ppm. Vertically,
the measured B_{0} magnitude decreases from 144.387 mT to
130.603 mT, with a constant gradient of 4.6 T/m from 0.15 mm to 3.15 mm above
the magnet surface. A planar radiofrequency coil is optimized according to the
signal-to-noise ratio level of the coil. A one-dimensional profiling experiment
on an oil film shows that a vertical resolution of approximately
1.7 μm can be achieved. As an application, the silicone
rubber insulators are measured using the NMR sensor. Results demonstrate that
the silicone rubber insulators with different service times can be
distinguished through the transverse relaxation time T_{2}
of the silicone rubber insulators.
