Swarm studies on elementary processes and ion–molecule reactions in low-temperature plasmas

Abstract

This paper deals with the presentation and discussion of some recent measurements on the interaction of electron and ion swarms in gases, with particular emphasis on flourinated gases. The processes to be discussed are related to electron impact ionization and attachment, including Penning ionization and electron detachment. Electron transport is discussed in mixtures of SF6 and fluorocarbon gases, where interesting regions of negative differential conductivity have been observed in C2F4, and apparent pressure dependences of the drift velocity in C4F8. Ion transport is discussed in terms of recent measurements on positive and negative ions in SF6 and Ar. Finally, the subject of ion–molecule reactions is illustrated with the dissociation and charge transfer processes of daughter ions in nitrogen. Throughout the paper, the advantages and limitations of both the pulsed Townsend technique and the drift tube-mass spectrometer are highlighted.