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8 April 2009 Electromagnetic acoustic transduction using a pulsed electromagnet
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Some early designs of Electromagnetic Acoustic Transducers (EMATs) used electromagnets to provide the strong magnetic field required for the transducer to operate. The advent of a new generation of permanent magnets such as NdFeB, with magnetic fields approaching 1T, meant that many EMAT designs switched over to using these small, compact and relatively inexpensive magnets. Typically, most modern EMATs make use of permanent magnets since they can exert high magnetic fields with compact structures. There are certain limitations when using permanent magnets, and their low Curie points of between 80-150C limit their practicality for high temperature testing without using water cooled transducers. In this work we have employed a pulsed electromagnet to provide the magnetic field. Pulsing the magnet dramatically reduces the average power required, keeping the supply more compact and less complex. It has the added advantage on ferritic steels, of resulting in much larger amplitude ultrasonic signals and improved signal to noise when compared with EMATs which use the strongest permanent magnets available.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
S. B. Palmer, J. F. Hernandez-Valle, and S. Dixon "Electromagnetic acoustic transduction using a pulsed electromagnet", Proc. SPIE 7294, Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2009, 72940T (8 April 2009);

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