Improving the signal amplitude of meandering coil EMATs by using ribbon soft magnetic flux concentrators (MFC)

► This paper presents a new method of improving the ultrasonic signal amplitudes from a meander line (ML) EMAT. ► A soft magnetic material (Fe 60V 10V 10B 20) has been used as a magnetic flux concentrator (MFC) to improve the magnetic field. ► A 2D numerical model has been developed for the MFC with magnet to calculate the improved magnetic field. ► The ML EMAT signal amplitude with MFC has been increased by a factor of two compared to the signal without MFC. This paper presents a new method of improving the ultrasonic signal amplitude from a meander line EMAT by using soft magnetic alloy ribbon (Fe 60Ni 10V 10B 20) as a magnetic flux concentrator (MFC). The flux concentrator is a thin soft amorphous magnetic material (Fe 60Ni 10V 10B 20) which is very sensitive to a small flux change. The MFC is used with the EMAT to improve the signal amplitude and it was observed that the peak signal amplitude increases by a factor of two compared to the signal without MFC. Two dimensional numerical models have been developed for the EMAT with MFC to quantify the improvement of the received signal amplitudes. Model calculations and experiments have been carried out for a wide range of ultrasonic frequencies (500 kHz–1 MHz) in different materials.