Contactless technique for low-frequency measurement of resistivity in nonmagnetic conductive tubes

In this paper, we present a precise technique for contactless measurement of resistivity in conductive tubes. The method is simply based on the determination of the phase angle of the complex mutual inductance between two coils working under low-frequency conditions. The first coil is placed around the tube, whereas the detecting coil is situated inside it. Study of the magnetic screening caused by the currents induced in the tube allows its conductivity to be determined. The use of low frequency guarantees the almost complete absence of the skin effect in such a way that the results are obtained in a very simple manner.