Electromagnetic effects occur in electrically heated glass melts. Sometimes this fact causes disadvantages but it also offers the chance to influence the glass flow beneficially. A Lorentz forece can be generated by a strong external magnetic field called "Fremdfeld" (foreign field). The Lorentz force in the "Eigenfeld" (eigenfield) that is caused by the magnetic field around the current density in the glass can be neglected. A specific Lorentz force in the "Eigenfeld of the electrode" occurs in electric glass melting using rod electrodes and results from the magnetic field around these electrodes. The numeric JENA-HLX code was employed to calculate the current density distribution for complex voltages and the temperature-dependent electric conductivity. The magnetic field was built up accordingt to the Biot-Savart law. A first computer calculation shows that the Lorentz force will become the second driving force besides buoyancy near electrodes, provided electrode currents are about 800 A or higher. A second numeric trial dealt with a side-wall, a bottom and a top electrode in R-S-T connection. Here the most significant effect occurred at side-wall electrodes, where horizontal velocities increased. The third test was carried out to learn more about the Lorentz force in an electrically heated crucible. Here the most interesting effects were to observe when a Fredfeld was appled to the electrically heated fluid. For instance, the forced glass melt rotation around the electrodes is reversed if this phase shift changes from 0 deg to 180 deg. To sum up, the Lorentz force offers various opportunities to control the glass flow.
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