Absolute densities of O and O_3 in the effluent of an atmospheric pressure plasma jet (kINPen) operated with He and Ar determined by molecular beam mass spectrometry

Abstract

The absolute densities of O and O_3 in the effluent of a kINPen, an atmospheric pressure plasma jet, are determined by molecular beam mass spectrometry. A nitrogen gas curtain surrounding the effluent provides a stable environment and prevents interactions with the ambient air. Both He and Ar were used as feed gas with admixtures of O_2 up to 1%. Measurements are performed at discharge voltages from 1600 to 3000 {textrm{V}}_{textrm{pp}} and at distances from 5.5 to 10.5 mm from the nozzle of the gas shielding device to the orifice of the mass spectrometer. The measured O atom densities are in the order of 1 times 10^{14}~{textrm{cm}}^{-3} to 2 times 10^{15}~{textrm{cm}}^{-3}, whereas the O_3 molecule densities are in the order of 1 times 10^{14}~{textrm{cm}}^{-3} to 5 times 10^{14}~{textrm{cm}}^{-3}, respectively, when operated in argon the plasma generates higher densities of reactive species. Additionally, a novel molecular beam chopper design with linear movement has been successfully tested in the mass spectromerty setup as an alternative to a rotating chopper.Graphic