DIFFUSION OF PULSED EDDY CURRENTS IN THIN CONDUCTING PLATES

Abstract

Pulsed eddy current response from plates of copper, aluminum and brass less than 1 mm in thickness was investigated. Voltage response from the driver/pickup coil configuration was fit with an expression that considers the time‐dependence of the pulse generated first, in air and second, when the probe is mounted on conducting plates. Characteristic times for expulsion out of and diffusion into the conducting volume, by the electromagnetic field, were considered. In the thin plate limit the characteristic time for diffusion within the plate varied linearly with conductivity and had a magnitude that scaled with the dimensions of coil and plate thickness, in agreement with the variation expected for electromagnetic diffusion in thin conducting plates.