Abstract
Direct observation on molten silicon convection during Czochralski crystal growth was carried out using doublebeam X-ray radiography system with solid tracer method. The observed particle path had a torus like pattern for crystal and crucible rotation rates as +1 and -1 rpm, respectively. The root-mean-square velocity for one specific tracer was 21 mm/sec. Moreover, it is found that a flow field with larger azimuthal velocity than the rotational velocity of the crucible exists just beneath the crystal, while the flow field with smaller or negative azimuthal velocity exists near the crucible wall. Numerical simulation containing fluid flow, heat conduction and heat exchange by radiation has been performed using the geometry of the same as furnace used for experiment. The calculated flow velocity and particle path were almost the same as the experimental results. It has also become clear from a comparison of flow-velocity field between experimental and calculated results that the modulation of azimuthal-flow field is caused by the Colioris force.
