The motion of slow positive ions in gases - Mobilities of potassium and nitrogen ions in nitrogen

Abstract

It was shown in part I that there is a need for further experimental data on the drift velocity W of ions in gases such as nitrogen and argon where there are still unresolved problems. In addition, measurements of quantities such as the diffusion coefficient D and mean energy e are required for ions in most gases since published data on these quantities are scanty. In principle, it is possible to determine these quantities by measuring both the drift velocity W and the ratio W/D for selected groups of ions in an apparatus combining a time of drift electrode system, similar to that used by Tyndall et al. (1928) and Tyndall (1938), with a lateral diffusion system similar to that used by Townsend (1925) for the measurement of the ratio W/D for electrons. The advantages of using a time of drift selector for the ions rather than, say, a mass spectrometer are first, that there is no pressure gradient between the selector and the diffusion apparatus, so that no differential pumping is necessary, and secondly, that not only are the ions selected but their mobility is measured at the same time.