Experimental matching method for the two-dimensional numerical simulation of micro-floating zone in laser heated pedestal

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Title:	Experimental matching method for the two-dimensional numerical simulation of micro-floating zone in laser heated pedestal
Authors:	P. Y. Chen;C. L. Chang;S. L. Huang;C. W. Lan
Contributors:	Department of Gemology, Meiho University, Pingtung 91202, Taiwan;Institute of Photonic & Optoelectronics, National Taiwan University, Taipei 10617, Taiwan;Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan;Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
Keywords:	experimental matching method;interface shape;laser-heated pedestal growth;YAG;single-crystal fiber;heat transfer;fluid flow
Date:	2010
Issue Date:	2011-09-22T05:07:32Z (UTC)
Abstract:	It has been verified by comparing with the shape of the molten zone in terms of the experiment and then analyze the simulation results. That is experimental matching method. The two-dimensional simulation was employed to study the melt/air and melt/solid interface shapes of the miniature molten zone formed in the laser-heated pedestal growth (LHPG) system. Using non-orthogonal body-fitting grid system with control-volume finite difference method, the interface shape can be determined both efficiently and accurately. During stable growth, the dependence of the molten-zone length and shape on the heating CO2 laser is examined in detail under both the maximum and the minimum allowed powers with various growth speeds. Finally, heat transfer and fluid flow in the LHPG system are analyzed near the deformed interfaces. The global thermal distributions of the crystal fiber, the melt, and the source rod are described by temperature and its axial gradient within length of ~10 mm. As compared with the growth of bulk crystal of several centimeters in dimension, natural convection drops six orders in magnitude due to smaller melt volume; therefore, conduction rather than convection determines the temperature distribution in the molten zone. Moreover, thermocapillary convection rather than mass-transfer convection becomes dominant. The symmetry and mass flow rate of double eddy pattern are significantly influenced by the molten-zone shape due to the diameter reduction and the large surface-tension-temperature coefficient in the order of 10-4~10-3. According to the analysis shown as above, the results could be further extended for the analysis of the concentration profile and study of horizontal growth.
Relation:	The 14Th Nano & Micro-system Technology Conference, Paper A02_04, Kaohsiung, Taiwan (2010)
Appears in Collections:	[Department of Gemology] Conference Papers

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