The Flow of Rarefied Gases in Vacum Systems and Problems of Standardization of Measuring Techniques

Abstract

The problem of rarefied gas flow in vacuum systems and particularly the effects of non-uniform gas distributions likely to occur in practice have been the subject of many recent detailed investigations. The results of these studies have in turn influenced the techniques used in obtaining meaningful measurements. A brief review of recent activities is followed by a discussion of dynamic gas flow conditions as they affect the various recommendations for standardization of system parameters, measurements and calibration techniques. Methods have been agreed for the determination of volume rate offlow for pumps. Some of the remaining problems are concerned with measurements involving non uniform and possibly non-isothermal gas flow in systems containing localised or distributed sources of gas and cryogenic, sorbing or gettering surfaces as pumps.