Determination of Thermal Accommodation Coefficients of Inert Gases on a Surface of Vitreous UO2at ~35°C

1982 ◽  
Vol 59 (1) ◽  
pp. 63-69 ◽  
Author(s):  
Lloyd B. Thomas ◽  
Sudarshan K. Loyalka

The accommodation coefficients of helium, neon, argon, hydrogen and oxygen, on a tungsten surface, are smaller at liquid-oxygen than at room temperature. The accommodation coefficients of the inert gases varies, at both temperatures, approximately as the square root of the atomic weights. The increase in the accommodation coefficient of helium, with the hot-working of the wire observed by Roberts (1930), has not been confirmed for heating times up to 30 hr.


Widely different values of the accommodation coefficients of inert gases at metal surfaces have been reported in the recent literature, but reasonably concordant results have generally been obtained by different workers when the flashing procedure of Roberts was used. This technique was therefore critically examined by Bremner, who concluded that the low values of Roberts were in error because the original thermal steady state was not attained. If this criticism is valid, then a reassessment of Roberts’s conclusions in the application of them to the chemisorption of gases on metals is necessary. We have therefore investigated, both theoretically and experimentally, the techniques employed by Roberts and Bremner, and have shown that the conclusions given by Roberts are substantially correct.


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