Effect of oxygen on thermocapillary convection in a molten silicon column under microgravity

X-ray flow visualization in a half-zone molten silicon bridge was carried o ut under microgravity at a variety of oxygen partial pressures in an ambien t atmosphere. The flow velocity of thermocapillary convection was found to decrease with increased oxygen partial pressure. Thermocapillary flow stabi lized when the oxygen partial pressure at the inlet P-O2 was increased to 1 0(-4) MPa. The dependence of the flow velocity and flow mode on p(O2), can be explained in terms of the decrease in the temperature coefficient of sur face tension due to the increase in oxygen partial pressure. (C) 2001 The E lectrochemical Society.