Mass spectrometer studies of the ion composition in the pink afterglow

Abstract

The time dependences of the ion number densities in the pink afterglow of nitrogen, as represented by the ion wall currents, have been measured. The ions were extracted through an orifice from a flow system and analysed by a quadrupol mass spectrometer. It has been found thatN ⁺₂ ions are dominating in the early afterglow. With the beginning of the ionization processN ⁺₃ and at pressure >6 TorrN ⁺₄ become the majority ions. The ratio of the number densities(N ⁺₃ )/(N ⁺₂ ) reaches a maximum during the increase of the ionization processes before the maximum is reached. This behaviour suggestsN ⁺₃ ions to be the primary ions created by the ionization processes. The time dependences of the ion number densities (N ⁺₂ ), (N ⁺₃ ) and(N ⁺₄ ) are found to vary similar, showing that the ions are strongly coupled by conversion processes.

The conversion processes are discussed.

In the maximum of ionization at a total pressure of 4.4 Torr the ratios of the number densities of the afterglow ions (N ⁺₂ )∶(N ⁺₃ )∶(N ₄ ⁺) are 1∶1.9∶0.64.