DISCUSSION OF THE EFFECT OF ROTATING MAGNETIC FIELD ON CRYSTAL GROWTH

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The electronic integrated circuits have been extensively developed to materialize the information technology society. The integrated circuits became more condensed and less energy dissipasive. The silicon wafer to constitute the base plate of the integrate circuit would become much more enlarged to become 14 to 16 inches diameter to reply for the increasing demand more efficiently. The crucible for manufacturing such a large rod would become much larger and the molten liquid of silicon would become more turbulent. To manufacture a single crystal rod safely and steadily, it would be necessary to calm the convection of the melt by applying a magnetic field from outside of the furnace. In the present research program, the rotating magnetic field is applied to see its effect on the convection of the liquid metal in a vertical cylindrical crucible. However, for this purpose, a little more simplified system of a cube was at first considered. The liquid metal in a cubic enclosure is heated an … More d cooled from opposing vertical walls with four other walls thermally insulated.Magnetic field was applied uniformly in parallel to both the hot and cold walls. At Ra = 10ィイD15ィエD1, Pr = 0.025 and Ha = 50, the average Nusselt number increased at least 5% than that without magnetic field. This contradicts to the common understanding that the magnetic field suppresses the convection and heat transfer rate (Paper 1). Then, a rotating magnetic field was studied theoretically for the liquid metal in a vertical cylinder. The numerical solution was successfully obtained for the dimensionless angular velocity Ω = 10ィイD13ィエD1 and 10ィイD14ィエD1 and Ha = 0.01 and 0.1. The maximum velocity occurred at 58% of the radius (Paper 2). Experimental approach was also carried out. However, the rotating magnetic field of static outer coil taken from a usual electric motor could not have rotated the gallium in a cylinder due to too much leakage of the magnetic field. After many trials, two coils rotating magnet successfully rotated the gallium. Less