Rotational Instability of a Long Liquid Column

Abstract

A liquid column is. apart from its intrinsic interest from the basic science point of view, a good mechanical model of a crystal growth process known as the floating zone technique. In this technique, rotation of the supporting rods is used to uniformize the usually non-axisymmetric temperature field otherwise produced by the directional heating. The theory of the influence of solid rotation on the stability limit is already available and early experimental results showed the existence of two different kinds of unstable shapes (in absence of other perturbations): the amphora mode and the C-mode. The existence of the amphora mode was realized in SL-D1 experiments but C-mode breakages could not be obtained, probably due to unexpected existence of body forces that always excited the amphora mode breakage. As none of these modes can be realistically simulated on Earth, an experiment in microgravity conditions (TEXUS-23) was performed in order to obtain C-mode deformations (not achieved up to now in a reproducible way). However, experiments on Earth using the Plateau Tank Technique have been performed in order to obtain more insight in the problem and to prepare experiments aboard sounding rockets. Results of the experiment aboard TEXUS-23 show a reasonably good agreement with the theoretical predictions.