THERMAL ACCOMMODATION COEFFICIENT FOR HELIUM ON PARTIALLY GAS COVERED PLATINUM IN THE TEMPERATURE RANGE 300-1400 K.

Hot wire type instruments have been used to determine thermal accommodation coefficient for helium on gas covered platinum in the temperature range 300-1400 K from heat transfer rate data taken in the temperature-jump regime. The platinum surfaces were prepared by prolonged heating at high temperatures in air at pressures of less than 7. 5 multiplied by 10** minus **9 Pa. The available information on adsorption of common gases on platinum suggests that the test surfaces were partially covered, primarily with oxygen. These accommodation coefficient values are compared with the available reported results of other workers. This work finds application in space flight, chemical reactors and catalysts.