拡散ポンプ排気速度測定におけるテストドームの影響

抄録

In the measurement of the pump speed of an oil diffusion pump by Dayton's method, the speed measured with a test dome of a larger diameter than that of the pump mouth shows a value smaller than the one obtained with test dome of the same diameter as the pump mouth.
The reason for it is considered to lie in that the former conductance is smaller than the latter, when a distance between the pump mouth and the measuring position is smaller than a mouth diameter.
We measured pressure distribution in an axial and a radial direction in a test dome and determined the conditions in the test dome for speed measurement.