Electromagnetic acoustic transducer (EMAT) system and a method for generating linear polarised transversal waves with variable predefined polarisation direction within a test piece

摘要

The system has a magnetization unit arranged on a surface of a test specimen (2) to produce parallelly oriented magnetic field to the specimen surface. A high-frequency (HF) coil arrangement (3) is settled on the surface for detecting a HF field occurring overlaid with the magnetic field. The magnetization unit comprises four magnetization bodies (1a-1d) arranged on the surface to introduce magnetic field lines with a predetermined magnetic flux into the specimen to change magnetic flux such that spatial direction of the magnetic field is changed in a predetermined manner. An independent claim is also included for a method for producing ultrasound waves in a form of linearly polarized transverse waves with variably predetermined polarization direction within a test specimen.