Analysis of the effect of design parameters on the sensitivity of electromagnetic-acoustic transducers

This work is a generalization of the results of practical investigations, carried out by the author and aimed at improving the electrical characteristics of electromagnetic-acoustic transducers (EMAT). The main task of the investigations was to determine the relationships between the design of the EMAT and its sensitivity (i.e., the transformation factor taking into account the signal/noise ratio). In the article, the experimental results are justified theoretically, and the analysis results are used to give recommendations for optimizing the design characteristics of EMAT. The efficiency of the EMAT depends on both the geometrical parameters of the design-dimensions, mutual position, the form of the elements of the transducer, generating the constant and alternating magnetic fields, and also on the electrical characteristics of excitation circuits and reception of the signal whose composition includes the inductances of the exciting and receiving coils of the transducer (EMA transducers with a single coil have the lowest signals like/noise ratio and, consequently, are not examined any further). Since the inductances of EMAT can be arbitrary if the possibilities of real electronic devices from the viewpoint of overloading by the interference and in the absence of restrictions of the power of the probing parts are not taken into account, the electrical characteristics of the coils of the transducer were determined on the basis of the restrictions on the power of excitation and the minimum debt time taking into account the specific structure of the input cascade of the amplifier.