LAUSR

Abstract The paper presents an eddy current system with an I-core sensor, intended for testing conductive materials in the shape of a cylinder with a small radius, such as coins or discs. The employment of the truncated region eigenfunction expansion (TREE) method allowed developing an analytical mathematical model, which at the design stage was used to determine the optimal parameters of the sensor. The final formulas presented in a closed form were implemented in Matlab, which made it possible to obtain a fast and effective program for determining the impedance of a sensor placed above a magnetic or non-magnetic cylinder. The constructed sensor has a removable core, so that it is possible to carry out measurements both with and without the core. The results of the measurements and calculations showed a good agreement, and the developed I-core sensor allowed obtaining much greater sensitivity than in the case of the air-core sensor.