| Figure 1. Construction details of an EMAT. (a) Simplified structure to show the essential parts – a wire to induce eddy currents in a conducting surface and a static magnetic field. (b) A meander line coil under a large permanent magnet pole. (c) A periodic array of magnets that apply alternating magnetic fields to an eddy current sheet flowing in a race-track pattern. EMATs are simply a coil of wire in a magnetic field. By pulsing an electrical current through the coil, an eddy current is induced in the surface of the nearby conductive material; the magnetic field interacts with this eddy current to produce a mechanical force on the surface to excite ultrasonic vibrations. The same configuration of coil and magnet also detects mechanical motion of the surface because the motion of a conductor in a magnetic field produces currents that are detected and measured by the near-by coil. |
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| EMAT Technology Ltd. |
