Abstract
The non-stationary mathematical model of pumping of gas, located in the volume and adsorbed on the inner surface of vacuum chambers is considered. A feature of the model is the use of variation of adsorption heat with respect to the logarithm of the degree of coverage obtained from the Frendlich adsorption isotherm. The relations between pressure, gas release, heat of adsorption, the amount of adsorbed gas and the pumping time are calculated. The existence of a regular pumping mode is shown. Experimental verification of the model confirms the theoretical calculations. The model makes it possible to specify the pumping time of International Thermonuclear Experimental Reactor vacuum chambers and to obtain a significant economic effect when selecting pumping means by reducing the safety factor.
Highlights
IntroductionIn addition to gas in the volume, may contain a large amount of gas adsorbed on its internal surfaces
Vacuum chambers, in addition to gas in the volume, may contain a large amount of gas adsorbed on its internal surfaces
The pumping time of the vacuum chamber is almost completely determined by the pumping time of adsorbed gases [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]
Summary
In addition to gas in the volume, may contain a large amount of gas adsorbed on its internal surfaces. A discussion of the adsorption model in the literature, for example, in [6], was made on the basis of [2] The disadvantage of this approach is the use of a linear relation between the adsorption heat and the degree of coverage, which is not fulfilled for the adsorption of water vapors on the walls of vacuum chambers. Experimental data on the adsorption of water on the surface of stainless steel are well described by the Frendlich isotherm equation [3]. In this model, we used the logarithmic dependence of the heat of adsorption on the degree of coverage [4, 5]. An experimental study of the curve of water vapor pumping from the surface of the vacuum chamber showed a satisfactory agreement between the theoretical calculations and the experiment
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