Development of molten metal holder of Faraday type

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This study was conducted for the development of a molten metal holder. The molten metal is held without contact by the electromagnetic force which is induced by the interaction between DC current and DC magnetic field. We determined the the shape of the free surface under various conditions. Transient response and frequency characteristics were also determined with relation to the feedback control. From the analysis and the experiments with mercury, following results were obtained.(1) Stable holding of the molten metal without contact can be realized by using an electromagnetic force.(2) When the electromagnetic force is irrotational, no flow is induced in the fluid. In case that the horizontal DC electric current and nonuniform vertical DC magnetic field which cross each other in right angle are applied to the molten metal, stable concave or convex surface is formed.(3) In case of the electromagnetic force with a rotational part, a recirculating flow is induced in the fluid ; however, the flow becomes weak as the magnetic field becomes strong. Various shapes of the free surface can be realized by changing both the position of the electrode and the distribution of the magnetic field.(4) When the electromagnetic force is suddenly applied, surface waves are generated. These waves disappear as the magnetic field becomes strong. There exists a suitable magnetic field strength to reduce the time required for the stationary surface to a minimum.(5) The AC part of the electric current make the surface unstable. Unsteady electromagnetic force causes the vertical or horizontal sloshing of the liquid metal. An increase of the Reynolds number or of the Weber number will make the system unstable but an increase of the Stuart number will make the system stable.