一种磁场优化结构电磁超声传感器设计*

为了进一步增强电磁超声检测技术在管道厚度测量领域的检测能力，该文对电磁超声传感器(EMAT)的结构进行了优化。提出了多磁铁对称分布型EMAT，能实现更小的磁铁体积，产生更强的表面剩磁强度。采用在硅钢表面开槽的方式限制涡流形成的区域，解决了涡流对测量的影响。建立厚度测量实验系统，对比出单磁铁型与多磁铁对称分布型EMAT在不同提离距离上检测信号的变化规律。结果表明，多磁铁对称分布型结构可通过增强EMAT的偏置磁场达到信噪比更优的效果。采用耐高温探头外壳和钐钴磁铁，提高了EMAT探头在高温环境下的检测性能。

A magnetic field optimized structure electromagnetic acoustic transducer design

In order to further enhance the detection capability of electromagnetic ultrasonic testing technology in the field of pipe thickness measurement, the structure of electromagnetic ultrasonic transducer (EMAT) is optimized in this paper. A multi-magnet symmetric distribution type EMAT is proposed, which can realize a smaller magnet volume to produce a stronger surface remanent magnetic strength. The influence of eddy currents on the measurement is solved by using slots on the surface of silicon steel to limit the area of eddy current formation. Establishment of thickness measurement experimental system, compared with a single magnet type and multi-magnet symmetric distribution type EMAT in different lifting distance on the change rule of the detection signal. The results show that multi-magnet symmetric distribution type structure can be enhanced through the EMAT bias field to achieve a better signal-to-noise ratio effect. The use of high-temperature resistant probe shell and samarium cobalt magnets improves the detection performance of EMAT probe in high temperature environment.