Abstract
The velocity and absorption of sound in He, Ne, and Ar have been measured at room temperature and pressures ranging from 6.0−0.3 torr. The gases were contained in a tungsten tube 0.953 cm i.d. Flashing this tube at approximately 1900°C in a high vacuum before the measurements produced a marked increase in the sound velocity and a marked decrease in the sound absorption. The effect has been attributed to a decrease in the thermal and momentum accommodation coefficients produced by removing the adsorbed gases from the tungsten surface. In the presence of mischmetal getter, the accommodation coefficients for the surface after flashing remained constant for a period of two weeks. When oxygen was admitted to the system momentarily to a pressure of a few torr and then pumped out, the sound velocity and absorption in the noble gases returned to values corresponding to higher accommodation coefficients. The effect was repeatable. Comparison of the measured absorption and velocity with theoretical curves places reasonable limits on the permissible values for the energy and tangential−momentum accommodation coefficients.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.