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In this work we have performed experimental research into the influence of ion dynamics on the profiles of the Hα and Hβ lines of the hydrogen Balmer series. In order to understand this influence the electron density of a microwave plasma column at atmospheric pressure is measured from the Stark broadening of both lines. However, in this case Kepple–Griem’s theory is not used, as usual, but a new computational model based on the μ-ion model that includes the effect of the ion dynamics on the profiles. The results obtained show that the difference between the electron density values from both the Hα and Hβ lines is about 3%. So, it is possible to use the Hα line for the diagnosis of the electron density in those cases in which it is not possible to use the Hβ line; for example, when the Hβ line is not intense enough.

Surface wave induced plasma (SWP) is a particular class of microwave induced plasma. It is used in atomic emission and mass spectrometry as a source of excitation for the elemental analysis of samples in analytical chemistry. This discharge is mainly used at powers less than 300 W. At such low power, an efficient process of desolvation, atomization, excitation and ionization of the analyte can only be reached provided the density of power absorbed in the discharge is large. This requires a plasma whose volume increases very little with increasing absorbed power. At atmospheric pressure in the SWP, such a volume limitation can be achieved by having the plasma extending into ambient air in the form of a flame (open air discharge). This article presents the results of the experimental characterization and study of the degree of thermodynamic equilibrium of an argon plasma flame produced by a surfatron. The values of the plasma parameters and b(p) (departure from equilibrium) parameter for the ArI levels show that the discharge is a two-temperature plasma. By comparing the results with those obtained for a classical surface-wave plasma column, it can be concluded that the plasma in flame is more suited to be used as a source of excitation in analytical chemistry, due to its higher electronic density and temperatures values.

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