| 摘要 |
PURPOSE:To eliminate the contamination caused oil vapor, etc., and to eliminate disadvantages owing to thermal decomposition, oxidation, etc. by using a turbo molecular pump in place of an oil diffusion pump. CONSTITUTION:A test sample 1 is evacuated by operating an evacuating system consisting of a throttling valve 2, a turbo molecular pump 5, a reverse diffusion valve 6, and an auxiliary pump 7, and while the sample 1 is swept with gaseous helium, the gaseous helium is detected with an analyzing pipe 3, whereby a leakage test is carried out. The sensitivity for detection of the helium changes with the change in the number of revolutions of the pump 5. When the number of revolutions lowers, the sensitivity for detection of the helium increases and at the same time the background increases as well. On the other hand, with respect to the stability of the helium output, when the number of revolutions of the pump 5 lowers, the output is unstable and this makes leakage measurement difficult. Hence, it is possible to obtain the sufficient sensitivity for detection of the helium by selecting the number of revolutions of the turbo molecular pump. |
