Formula for Thermal Accommodation Coefficients

A simple formula in closed form is proposed for the thermal accomodation coefficient from which the accommodation coefficient of a monatomic gas—solid system may be calculated from certain basic parameters of the system. The formula α(T)=1−exp(−T0/T)+α(∞) tanh{[(MT)1/2/α(∞)](a/λ)} exp(−T0/T)is obtained from consideration of certain aspects of Goodman's lattice theory of accommodation and from conclusions regarding certain properties of available experimental data. Adequate agreement is obtained of the formula with both the lattice theory and experimental data. Certain, corrections are applied to the lattice theory, and the gas—surface-potential interaction parameters relevant to the lattice theory are revised.