Flow of binary gas mixtures through small sampling orifices

Abstract

Species-dependent density changes in binary gas mixtures flowing through a small thin orifice (thickness similar to 10% of diameter) have been studied experimentally using an ion drift tube, covering a limited range of the transition regime from molecular to hydrodynamic flow. The observed density changes are found to depend strongly on the mass ratio of the two flowing gases. A semiempirical formula that estimates the density changes has been derived by fitting the experimental data.