Observation of periodic thermocapillary flow in a molten silicon bridge byusing non-contact temperature measurements

Thermocapillary flow in a bridge of molten silicon under measured oxygen pa rtial pressure in the ambient atmosphere was investigated in terms of fluct uations in the brightness of pixels of CCD images. The fluctuations in the brightness of the CCD images at the silicon surface agree with the temperat ure fluctuations measured in the bridge by using thermocouples in a mono-el lipsoidal mirror furnace. Moreover. a mode with periodic fluctuations in pi xel brightness was found when the temperature difference between the upper and lower interfaces of the bridge decreased from 24.5 to 7.5 K. The Marang oni number corresponding to this temperature difference was estimated to be 700-1700. (C) 2001 Elsevier Science B.V. All rights reserved.