Molecular Flux Density Distribution at the Pump Flange of a Test Dome for Measuring the Speed of a High Vacuum Pump

Abstract

A numerical analysis has been obtained on the distribution of the molecular flux density qo(r) at the pump aperture of a test dome for measuring the speed of a high vacuum pump. The caluculation was carried out based on solving Clausing's integral equation by using iterative approximation method. It is found that qo(r) slightly decreases with increasesing radius, which might not affect the accuracy of measurement of the speed of the pump. For further consideration of the basic aspect of this phenomenon, numerical analysis was also carried out for cylindrical tube. Similar tendency was resulted on the molecular flux density distribution at the exit of the cylinder.