Measuring the conductivity profile of trepanned graphite samples using Electromagnetic Induction Tomography

S. Pennya, A. Fletchera, W Yina, D. Armitagea, A. Peytona, R. Chapmanb, M. Brownc

a School of Electronic and Electrical Engineering, University of Manchester, M60 1QD, UK

bNDT Consultant, Dursley, Gloucester, GL11 4EW, UK

c EDF Energy, Barnwood, Gloucester, GL4 3RS, UK

Abstract

This paper discusses the use of Electromagnetic Induction Tomography (EMT) to measure the impedance of cylindrical graphite samples and to reconstruct the axial electrical conductivity profiles. The measurements are taken as the samples pass through a circular array of eight coils, operating with an excitation frequency of 40 kHz. The conductivities of these samples are then separately measured using a four point probe. A set of reference samples was used to compile a data set, which, by comparing the results, allowed a relationship between the measurements of mutual inductance and the absolute conductivity of the samples to be determined.

Keywords: Non-destructive testing, Electromagnetic Induction Tomography, image reconstruction, Graphite