This article presents an eddy current probe with array tunnel magnetoresistance (TMR) sensors for inspection of the steam generator tube of the nuclear power plant. The TMR sensors are integrated on a circular printed circuit board (PCB) with the sensitive axis along the radius directions. The dimensions of each TMR sensor in the array are length (0.45 mm) × width (0.45 mm). Fine spatial resolution magnetic field imaging can be generated as the size of the sensor is small. The operating principle of the probe is based on Faraday's law, where eddy current is induced in the tube wall by an excitation coil carrying ac current, and then, the disturbance of the eddy current is monitored in terms of the magnetic field measured by the TMR sensors. Thanks to the high sensitivity and fine spatial resolution of the TMR sensors, the probe is capable of detecting outer diameter (OD) defect with an effective size 0.127 mm × 0.436 mm. Moreover, when the probe scans in a defect-free area, the variation of lift-off of the probe to the inner surface of the tube wall does not bring in noises, which is important for maintaining a high signal-to-noise ratio in the practical inspection. The operation principle of the probe was studied based on a finite-element method (FEM) model, and then, a prototype unit was developed and tested. The experimental results demonstrated the feasibility of the concept and validated that the probe has excellent ability to detect various defects.

中文翻译：

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用于管道检测的带有集成隧道磁阻阵列传感器的涡流探头


本文介绍了一种带有阵列隧道磁阻 (TMR) 传感器的涡流探头，用于检查核电站的蒸汽发生器管。 TMR 传感器集成在圆形印刷电路板 (PCB) 上，敏感轴沿半径方向。阵列中每个 TMR 传感器的尺寸为长 (0.45 mm) × 宽 (0.45 mm)。由于传感器尺寸较小，因此可以生成精细的空间分辨率磁场成像。探头的工作原理基于法拉第定律，通过承载交流电流的励磁线圈在管壁中感应出涡流，然后通过 TMR 测量的磁场来监测涡流的扰动。传感器。得益于TMR传感器的高灵敏度和精细空间分辨率，该探头能够检测有效尺寸为0.127 mm × 0.436 mm的外径（OD）缺陷。此外，当探头在无缺陷区域进行扫描时，探头相对于管壁内表面的提离变化不会带来噪声，这对于保持高信噪比非常重要。实际检验。基于有限元法（FEM）模型研究了探头的工作原理，然后开发了原型装置并进行了测试。实验结果证明了该概念的可行性，并验证了该探头具有优异的检测各种缺陷的能力。