Separation of Light Isotopic Gas Mixtures in the Thermal Diffusion Column

Abstract

The theory of the thermal diffusion column, originally developed by Jones and Furry for mixtures of heavy isotopes, is extended to include mixtures of light isotopes, the properties of which depend on composition. The transport equation which results is similar to previous equations for mixtures of heavy isotopes, but atom fractions are replaced by mass fractions. Experimental separation measurements of the ³He–⁴He system were used to test the theory. The predicted effect of ³He concentration on the reduced initial transport coefficient is closely followed experimentally. The general agreement between theory and experiment is within the mutual uncertainties of the experiments and of the calculations. The uncertainty in the experimental column transport coefficients is estimated to be ± 9%, and the uncertainty in the coefficients calculated from theory is estimated to be ± 5%. The theory is also expected to apply to the separation of mixtures of unlike gases, although this aspect was not tested experimentally.