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A physical model for electromagnetic control of local temperature gradients in a Czochralski systemCramer, A.; Röder, M.; Pal, J.; Gerbeth, G.
The shape of the solidification front and the related mono-crystalline growth in the Czochralski crystal growth process is thought of being strongly influenced by the ratio of the horizontal and the vertical temperature gradient r* = deltaT_h / deltaT_v at the triple point liquid-solid-atmosphere, which ratio desirably should be in the order of unity. A liquid metal model experiment was therefore built that allows studying r* under the influence of magnetic fields. The cylindrical liquid metal column was homogeneously heated from below, whereas on top the heat was extracted in a centrical region covering only one third of the surface in order to simulate the growing crystal. Without flow control, r* ≈ 3 is far removed from unity. It was then possible to reach the target value r* = 1 for any temperature difference between the bottom and the top at a moderate field strength while applying a rotating magnetic field.
Keywords: crystal growth, Czochralski process, flow control, electromagnetic processing of materials, magnetic fields
International Scientific Colloquium on Modelling for Material Processing, 16.-17.09.2010, Riga, Lettland
Contribution to proceedings
International Scientific Colloquium Modelling for Material Processing, 16.-17.09.2010, Rīga, Latvija
Proceedings of the 6th International Scientific Colloquium Modelling for Material Processing, 978-9984-45-223-4, 41-46
- Magnetohydrodynamics 46(2010), 353-362
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