In this work, the influence of dry air on the electron density (ne) and electron temperature (Te) in a cascaded arc Ar plasma is firstly studied by the state-of-the-art laser Thomson scattering approach. The results reveal that a small amount of dry air can induce a sharp drop in ne, which is ascribed by the dissociative recombination reactions between electron and molecular ions formed in charge transfer reactions. With the increase in dry air ratio, Te exhibits a non-monotonic trend which initially increases and then decreases. This should be caused by the cooperation between super-elastic collision with highly vibrationally excited molecules and electron impact vibrational excitation to molecules. Additionally, the calculated electron density (necal) and electron temperature (Tecal) are derived using ne and Te obtained from the separate additions of N2 and O2, along with the respective proportions of N2 and O2 in dry air. It is found that both necal and Tecal closely match the experimentally measured values in dry air, which indicates that the impact on ne and Te are mainly dominated by N2 and O2 molecules and the interplay between nitrogen and oxygen, has minimal effect on the plasma parameters.
This paper investigates how adding dry air affects the electron density and temperature in an argon plasma generated by a cascaded arc. The results show that a small amount of dry air can significantly reduce electron density, while electron temperature exhibits a non-linear trend. The authors also calculate the expected changes based on the individual effects of nitrogen and oxygen, finding good agreement with the experimental data.