College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, China.
Shenzhen Academy of Aerospace Technology, Shenzhen 518057, China.
Sensors (Basel). 2023 Jun 9;23(12):5476. doi: 10.3390/s23125476.
In this study, an optimized unilateral magnetic resonance sensor with a three-magnet array is presented for assessing the aging of composite insulators in power grids. The sensor's optimization involved enhancing the static magnetic field strength and the homogeneity of the RF field while maintaining a constant gradient in the direction of the vertical sensor surface and maximizing homogeneity in the horizontal direction. The center layer of the target area was positioned 4 mm from the coil's upper surface, resulting in a magnetic field strength of 139.74 mT at the center point of the area, with a gradient of 2.318 T/m and a corresponding hydrogen atomic nuclear magnetic resonance frequency of 5.95 MHz. The magnetic field uniformity over a 10 mm × 10 mm range on the plane was 0.75%. The sensor measured 120 mm × 130.5 mm × 76 mm and weighed 7.5 kg. Employing the optimized sensor, magnetic resonance assessment experiments were conducted on composite insulator samples utilizing the CPMG (Carr-Purcell-Meiboom-Gill) pulse sequence. The T distribution provided visualizations of the T decay in insulator samples with different degrees of aging.
本研究提出了一种优化的单边磁共振传感器，采用三磁铁阵列，用于评估电网中复合绝缘子的老化情况。该传感器的优化涉及增强静态磁场强度和射频场的均匀性，同时保持垂直传感器表面方向的恒定梯度，并使水平方向的均匀性最大化。目标区域的中心层位于线圈上表面下方 4 毫米处，导致该区域中心点处的磁场强度为 139.74 mT，梯度为 2.318 T/m，相应的氢原子核磁共振频率为 5.95 MHz。在平面上 10mm×10mm 范围内的磁场均匀性为 0.75%。传感器尺寸为 120mm×130.5mm×76mm，重量为 7.5kg。采用优化后的传感器，利用 CPMG（Carr-Purcell-Meiboom-Gill）脉冲序列对复合绝缘子样品进行了磁共振评估实验。T 分布提供了不同老化程度的绝缘子样品 T 衰减的可视化。
