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.

He 和 N _{2 的}气体混合物中的第一汤森电离系数α与大气压等离子体射流的发展和化学活动的建模有关。本研究根据稳态非自持汤森放电装置中电流与电极间距的测量值确定了α。测量是在 10-800 Torr 的绝对压力范围和20-1000 Td 的减小电场E/N范围内进行的。气体混合物中N ₂浓度对密度归一化电离系数α/N 的影响取决于减小的电场强度E/N。在E/N低于 200 Td 的值，增加 N ₂含量会降低α/N而当E/N值高于 200 Td 时，增加 N ₂含量会增加α/N的平台值。在使用 Bolsig+ 执行的计算和测量的α/N之间观察到相当好的巧合。在混合物中N ₂百分比低于 5% 和E/N值低于 200 Td 时，实验结果与计算之间的差异可归因于 Penning 效应。