Temperature differences ranging from 100°C to 500°C were maintained between the top and bottom ends of vertical capillaries containing liquid metal. The light isotope was found to be enriched at the hot end. The steady-sate isotope separation for different temperature ranges were between 1 and 3 per cent, corresponding to the thermal diffusion factors αK=3.1×10-2, αRb=3.1 × 10-2 and αGa=3.8 × 10 -2. According to a theoretical model, the results imply that the diffusing species is a “cluster” of several cooperating atoms, the mean diffusive displacement of which is considerably less than the effective cluster diameter. The clusters drift into voids given by the statistical fluctuations of free volume.
Recent progress in isotope separation by a thermal diffusion method.