Low Temperature Transport Properties of Gases. I. Helium

Abstract

Values have been computed for the viscosity, thermal conductivity, and coefficient of self-diffusion of gaseous helium for temperatures below 200°K by application of classical scattering theory within angular regions where diffraction effects are absent. Values of classical total collision cross sections are obtained which are used to evaluate classical cross sections for viscosity, thermal conductivity, and self-diffusion appropriate to a Maxwellian gas. Numerical values of the transport properties are obtained by substitution of the appropriate classical cross sections into the exact transport property formulas of Chapman and Enskog. In the region 200° — 14°K, the average absolute deviations between calculated and experimental values are 1.9 percent for viscosity and 4.6 percent for thermal conductivity. Extrapolation of calculated viscosity values to 1.64°K appears to be justified on the basis of agreement with experimental values. It cannot be stated that similar extrapolation in the case of thermal conductivity is valid because of possible uncertainties in the experimental values between 3.95° and 1.62°K. Values of the self-diffusion coefficient have been calculated between 200° and 5°K, but experimental values are not available for comparison.