Electromagnetic ultrasound transducer
AssigneeFraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
InventorFrank Niese
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Abstract
An electromagnetic ultrasound transducer is disclosed for receiving linearly polarized horizontal shear waves from an electrically conductive workpiece including a magnetizing unit, which provides a side facing the workpiece, along which a number n of permanent magnets are attached in at least two rows arranged next to one another in such a manner that the magnetic polarities of the magnetic poles which face the side alternate along a row periodically with a period length which corresponds to a trace wavelength λs and a HF coil arrangement with conductor sections in at least two rows running parallel to one another, through which current can pass in mutually opposite directions.
Claims26
An electromagnetic ultrasound transducer for receiving linearly polarized horizontal shear waves from an electrically conductive workpiece comprising:
- a magnetizing unit with a side facing the workpiece, along which a number n of first permanent magnets are attached in each of at least two first rows so that magnetic polarities of the magnets facing the side of the workpiece alternate periodically along the first rows with a period length corresponding to a trace wavelength λs with n being an integer greater than 1;
- a HF coil with conductor sections disposed along at least two first rows running parallel to each other and through which current can pass in mutually opposite directions;
- n second permanent magnets in each of at least two second rows with magnetic polarities of the magnets facing the side of the workpiece so that the n second permanent magnets periodically alternate along the at least two second rows with a period length corresponding to the trace wavelength λs;
- an additional HF coil with conductor sections disposed along at least two second rows running parallel to each other and through which current can pass in mutually opposite directions;
- and wherein
- the at least two second rows of the n second permanent magnets are offset by half a trace wavelength λs from the at least two first rows of the n first permanent magnets to form n+1 lines so that a second line to a nth line contains first and second permanent magnets from the first and second rows, a first line contains only first permanent magnets and a n+1th line contains only second permanent magnets;
- the two first rows of the n first permanent magnets are located next to one another;
- and
- the two second rows of n second permanent magnets are located next to one another and adjoin one of the two first rows of the n first permanent magnets.
An electromagnetic ultrasound transducer for receiving linearly polarized horizontal shear waves from an electrically conductive workpiece comprising:
- a magnetizing unit with a side facing the workpiece, along which a number n of first permanent magnets are attached in each of at least two first rows so that magnetic polarities of the magnets facing the side of the workpiece alternate periodically along the first rows with a period length corresponding to a trace wavelength λs with n being an integer greater than 1;
- a HF coil with conductor sections disposed along at least two first rows running parallel to each other and through which current can pass in mutually opposite directions;
- n second permanent magnets in each of at least two second rows with magnetic polarities of the magnets facing the side of the workpiece so that the n second permanent magnets periodically alternate along the at least two second rows with a period length corresponding to the trace wavelength λs;
- an additional HF coil with conductor sections disposed along at least two second rows running parallel to each other and through which current can pass in mutually opposite directions;
- and wherein
- the at least two second rows of the n second permanent magnets are offset by half a trace wavelength λs from the at least two first rows of the n first permanent magnets to form n+1 lines so that a second line to a nth line contains first and second permanent magnets from the first and second rows, a first line contains only first permanent magnets and a n+1th line contains only second permanent magnets;
- and
- the first and second rows of the n permanent magnets are interleaved in an alternating sequence and are located next to one another.
Dependencies are inferred from the claim text.