Computer Simulation of an Analytical Direct Current Glow Discharge in Argon: Influence of the Cell Dimensions on the Plasma Quantities

Abstract

A set of three-dimensional mathematical models was developed for describing the behavior of the different plasma species in a direct current glow discharge in argon used as an analytical ion source for mass spectrometry. The models were applied to cylindrical cells (flat cathode and hollow anode) with various dimensions to study the effect of the dimensions on the calculated plasma quantities. The results show that the cell dimensions have no significant influence on the qualitative behavior of the plasma quantities, but they do affect the absolute values, at least for cell dimensions ranging from 0.5 to 2 cm. For larger cells, the absolute values also remain more or less constant. The results suggest that, for the selected discharge conditions of 1000 V, 1 Torr and about 2 mA and a copper cathode, a cell with both length and radius equal to 2 cm is a good choice for analytical mass spectrometry. This paper demonstrates that the models are in principle able to predict trends in plasma behavior and performance in analytical applications and that they can therefore be useful in developing new cells.