Thermoelectric detection of the magnetic field by fluxgate gradiometer on subsurface tin inclusions embedded in a copper bar

A comparison between published analytical results with measured experimental results of the magnetic field produced by thermoelectric currents of subsurface semi-spherical pure tin inclusions embedded in a copper bar under the influence of an external heating and cooling into the specimen is presented. The measurements were taken from a 12.7 mm-thick copper bar with different subsurface semi-spherical pure tin inclusion diameters and lift-off distances between the sensor tip and specimen surface varied from 12.7 to 3.18 mm and from 1 to 8 mm, respectively. The experimental magnetic flux density measurements show a reasonable agreement as compared to analytical data as a function of the lift-off distances with the different inclusion diameters with the exception of the intrinsic material background magnetic signal that affected deeply the detectability of subtle imperfections in noncontacting thermoelectric measurements.