Liquid diffusion experiments, conducted using micro-gravity isolation mounts had shown that g-jitter significantly increased the measured solute diffusion coefficients. In some experiments, milli-g forced vibration was superposed on the sample when isolated from ambient g-jitter. This resulted in markedly increased solute transport. To explore the effects, arising in such long capillary diffusion couples due to the absence of Earth and the presence of forced g-jitter, the effects of a 1milli-g forcing vibration upon mass transport in a 1.5mm-diameter long capillary diffusion couple were simulated. In addition, comparative experiments involving Au, Ag and Sb diffusing in liquid Pb were carried out using a similar micro-gravity isolation mount; but under terrestrial conditions. It was found that buoyancy-driven convection could persist in the liquid; even when conditions were arranged to give a continuously decreasing density gradient up the axis of a vertical long capillary diffusion couple, due to the presence of small radial temperature gradients.

The Measurement of Solute Diffusion Coefficients in Dilute Liquid Alloys - the Influence of Unit Gravity and g-Jitter on Buoyancy Convection. R.W.Smith, B.J.Yang, W.D.Huang: Annals of the New York Academy of Sciences, 2004, 1027, 110-28