DEVELOPMENT OF NEW FLOATING ZONE APPARATUS WITH DOUGHNUT STYLE ELLIPSOIDAL MIRROR

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New floating zone apparatus with a doughnut style ellipsoidal mirror was designed and produced to uniform temperature distribution along the horizontal direction for growth of perfect superconducting oxide crystals. To design the doughnut style ellipsoidal mirror, the optimum shape of the mirror was determined to be 120 mm of the long axis, 96 mm of the short axis and 144 mm of the focus distance by computer-simulation. The mirror was produced experimentally from a specia aluminum alloy, and the surface inside the mirror was gold-coated to reflect the infrared lay effectively from the heat source. Also the semicircular halogen lamps to be adjusted in the mirror were designed and produced experimentally. The horizontal distribution and vertical gradient of temperature in the new apparatus were remarkable uniform and slow as compared with the commercial infrared heating apparatus.