The thermalhyphen;diffusion factor,agr;T, for the neonndash;xenon system has been measured from 328deg;ndash;873deg;K at seven compositions ranging from 5percnt;ndash;95percnt; neon. These measurements were made with a 20hyphen;tube trennschaukel where the pumping rate, the quantity of gas pumped, the duration of the experiments, and the temperature gradient could be varied over a wide range. This flexibility allowed the operating conditions to be chosen so that the theoretical corrections for trennschaukel operation were small and therefore could be applied to the measured separations with confidence. The present corrected data have been compared with theoretical calculations based on the Lennardhyphen;Jones (12ndash;6) potential and the modified Buckingham (exphyphen;6) potential. Both the experimental data and the theory indicate that the reciprocal ofagr;Tis a linear function of the composition. The present data agree well with the results of Grew and of Heymann and Kistemaker, but do not agree with that of Saxena and cohyphen;workers nor with the results of Atkins, Bastick, and Ibbs. The mutual diffusion coefficient for neonndash;xenon, which was derived from the measured composition dependence ofagr;T, agrees well with experimental diffusion coefficients reported in the literature and also with values calculated from experimental viscosity and thermal conductivity data. Although the values ofagr;Tare in disagreement with the present work, the composition dependence ofagr;Treported by Saxena, Nain, and Saxena also appears to be consistent with the values of the diffusion coefficient; however, that reported by Atkinset al. and Mathur and Saxena are not.
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