New developments on contactless inductive flow tomography

The contactless inductive flow tomography (CIFT) allows to visualize the mean flow structure in liquid metals by measuring the flow induced magnetic field perturbations under the influence of one, or several, applied magnetic fields. The reliable measurement of these very small field changes, and the involved mathematics to solve the inverse problem, are the main challenges for this flow inference method. We demonstrate the applicability of CIFT for various model experiments devoted to the continuous casting process, by employing a new measurement system using induction coils and AC excitation. This enables the determination of the flow structure even in the presence of a strong static magnetic brake field which is often used in continuous casting for controlling the flow in the mold. Additionally, we present preliminary results of CIFT applied to a thermally driven flow with some similarity to Czochralski silicon crystal growth. Due to the low velocities in the order of 1 cm/s, the dynamic range of the measurement system has to be enhanced by about one order of magnitude in comparison with the continuous casting application.