A General Study of Diffusion Pumps--Langmuir Type

Citation

Ho, Tseng-Loh (1931) A General Study of Diffusion Pumps--Langmuir Type. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/q69g-yd50. https://resolver.caltech.edu/CaltechTHESIS:03052024-215825836

Abstract

[Summary] It has not been possible to calculate theoretically the speed of the currently used diffusion pumps after Langmuir, because, unlike the Gaede's original type of diffusion pump, they have the vapor jet and the wide slit which prevent us from formulating the exact condition of the dispersed vapor through the so-called slit. The factors concerning the speed have been theoretically discussed and qualitatively verified by experiments. The experimental investigation is chiefly on the dependence of speed on vapor pressure, fore pressure, temperature of cooling system, kind of vapor used, kind of gas to be extracted, size of pump and form of jet; and the related experimental facts of previous workers are also discussed and referred to. Some of the results on speed can be stated definitely as follows: The speed is independent of the fore pressure when it is far from critical. The speed decreases as vapor pressure increases except at low vapor pressure, at which it has a maximum. The speed is nearly inversely proportional to the square root of the molecular weight of the gas to be extracted. The speed is independent of the pressure at which the pump works. As the temperature of the cooling system decreases the speed first increases and then reaches a constant. The speed of n-butyl phthalate vapor pump is greater than that of the mercury vapor pump. The speed of pump with divergent nozzle is greater than that with straight nozzle.

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