For metallic melts electromagnetic levitation provides an elegant method of noncontact containerless measurement, eliminating most interactions between the sample and its environment. This technique has been used in the past mainly for the study of highly reactive melts at high-temperatures. The sample, assuming a simple spherical shape, is contained in a clean environment and can be studied over a large temperature range. Temperatures again have to be measured with a pyrometer. An electromagnetic levitation device employs inhomogeneous radio-frequency electromagnetic fields to heat and position the samples. Such a field has two effects on a conducting, diamagnetic body. First, it induces eddy currents within the material, which, due to ohmic losses, eventually heat up the sample by inductive heating, and second, it exerts a Lorentz force on the body, pushing it towards regions of lower field strength. The latter effect can be used to compensate the gravitational force.
Institut of Experimental Physics
Graz University of Technology
ao. Univ.-Prof. Dr.
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