Experimental determination of first Townsend ionization coefficient in mixtures of He and N2. (1st June 2021)

• Record Type: Journal Article
• Authors: Talviste, Rasmus; Paris, Peeter; Raud, Jüri; Plank, Toomas; Jõgi, Indrek
• Is Part Of: Journal of physics. Volume 54:Number 32(2021)
• Publication Date: 2021-06-01
• Subjects: Townsend discharge -- ionization coefficient -- He and N2 mixtures; Physics -- Periodicals; 530
• DOI: 10.1088/1361-6463/ac0219
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: First Townsend ionization coefficient α in gas mixture of He with N2 is relevant for modeling of the development and chemical activity of atmospheric pressure plasma jets. This study determined α from measurements of current versus electrode separation in a steady-state non-self-sustaining Townsend discharge set-up. The measurements were carried out in absolute pressure range of 10–800 Torr and reduced electric field E/N range of 20–1000 Td. The effect of the N2 concentration in the gas mixture on the density normalized ionization coefficient α/N depended on the reduced electric field strength E/N . At E/N values below 200 Td, increased N2 content reduced the α/N while at E/N values above 200 Td, increased N2 content increased the plateau value of α/N . Reasonably good coincidence was observed between calculation performed with Bolsig+ and measured α/N . The discrepancy between experimental results and calculations at N2 percentage in the mixture below 5% and E/N values below 200 Td can be attributed to the Penning effect.