A model for pulsed Rayleigh wave and optimal EMAT design

A model has been developed for the prediction of the transient displacement of a Rayleigh wave generated by an electromagnetic acoustic transducer (EMAT), operating on the Lorentz principle. This model can be used to calculate Rayleigh waves of arbitrary forces. A linear coil and a spiral coil are considered as two examples. Out-of-plane displacement of the Rayleigh wave is measured experimentally using a Michelson laser interferometer. Good agreement is observed between the calculated and the measured results, demonstrating the value of this method. This paper explains how the Lorentz forces due to the static and dynamic magnetic fields work constructively and destructively, indicating that the orientation of the external magnetic field must be correct to achieve an efficient generation of the Rayleigh wave.