Remote Focus Field Electromagnetic Sensing Diagnostic System for Nondestructive Testing
Zhaohu Yu, Gui Yun Tian, Bin Gao, David Ong, Rui Chen · IEEE Transactions on Instrumentation and Measurement · 2025
In many industrial infrastructure fields, buried steel structures are susceptible to corrosion, necessitating effective non-excavation remote field detection methods. This paper proposed a novel remote focus field electromagnetic sensing detection technology, systematically coupling the pulsed eddy current (PECT) with the planar focus remote-field eddy current (PRFEC) sensing structure. In particular, it utilizes the unique high-shielding transmitting-sensing structure (magnetic shield box, orthogonal coils and tunnel magnetoresistance (TMR)) to construct a long-distance focus electromagnetic sensing diagnostic system. The high-shielding magnetic circuit structure enhances the electromagnetic coupling performance in space, and projects the primary magnetic field with the coils, forming a focused electromagnetic remote field. Both simulation and experiments have been conducted to validate the proposed method, which physically fuses PEC and RFEC, making full use of their advantages to detect long-range corrosion defects in buried steel structures with improved spatial resolution. By compared with different probe structures, the advantages of the proposed probe in terms of focusing magnetic field and remote field detection sensitivity were highlighted.