Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1689221 | Vacuum | 2016 | 10 Pages |
•We show a new technology for measuring momentum accommodation coefficients.•We measure momentum accommodation at the free molecular flow limit.•We successfully use a gas bearing stage in vacuum.•The measured momentum accommodation values range between 0.7 and 1.
An experimental technique using spin-down of a disk approaching the free-molecular flow limit is developed to measure the tangential momentum accommodation coefficient σt. The new technique uses a disk mounted on a shaft supported by gas bearings in vacuum. A differential scavenging system allows disk spin-down experiments in different gases. Representative test results with two different materials in two different gases are shown, demonstrating the method is capable of handling a range of gases, as well as any material that is available as, or can be formed into, a planar disk.