基于Halbach原理的电磁超声换能器永磁铁设计

在实际应用中，电磁超声换能器（electromagnetic acoustic transducer，EMAT）的转换效率低是一个普遍存在的问题，如何提高其检测效率是研究的重点。为了提高接收信号的幅度，对比了两种永久磁铁结构，选定了一种基于Halbach阵列的永磁铁的新型结构模型。对磁铁的提离距离做了仿真分析与实验研究，得出最合适的提离距离为2mm。通过理论计算与有限元方法的大量仿真与结构优化，验证了其结构的可行性与有效性。结果表明，新型EMAT结构能够有效提高接收信号的幅度，信噪比大约是传统EMAT结构的1.9倍。

Electromagnetic ultrasonic transducer permanent magnet design based on Halbach principle

The low conversion efficiency of electromagnetic acoustic transducer (EMAT) is a common problem in practical application. How to improve the detection efficiency is focus on the research. In order to improve the amplitude of the received signal, two permanent magnet structures were compared. A new structural model of a permanent magnet based on the Halbach array was selected. The distance from the distance was simulated and experimentally analyzed, and the most suitable lift-off distance was 2 mm. Through theoretical calculations and a large number of simulation and structural optimization of the finite element method, the feasibility and effectiveness of the structure are verified. The result shows that the EMAT structure of the new permanent magnet can effectively improve the amplitude of the received signal. The signal to noise ratio is approximately 1.9 times of the traditional EMAT structure.