Generation of reactive atomic species of positive pulsed corona discharges in wetted atmospheric flows of nitrogen and oxygen

The emission spectra of excited radicals (OH (A²Σ), O (3p⁵ P), H_α (³P)) and emissive species (N₂⁺(B₂ Σ_u⁺) N₂ (C³Π_u)) produced by positive pulsed high-voltage needle-plane corona discharges in atmospheric N₂ and O₂ flows wetted with 10% H₂O at 80 °C are used to investigate the relative concentrations of the produced radicals. The results indicate that the tendencies of the concentrations of radicals with discharge conditions are similar to each other due to their similar excitation processes by electron collision. The influence of oxygen flow mixed with the nitrogen flow on the emission intensities of O (3p⁵P→3s⁵ S₂⁰), Hα (3P→2S), N₂⁺ (B² Σ_u⁺→X² Σ_g⁺0-0), and N₂ (C³Π_u→B³Π_g 1-0) is presented. When the flow rate of oxygen addition is varied from 0–30 ml min⁻¹, the emission intensities of O (3p⁵P→3s⁵S₂⁰), Hα (3P→2s), and N₂⁺(B² Σ _u⁺→X²Σ⁺_g 0-0) increase and reach a maximum. Then, if the oxygen flow rate increases further, the emission intensities tend to decrease. However, the intensity of N₂ (C₃Π_u→B₃Π_g1-0) decreases monotonously with the increasing oxygen flow, which indicates that the electron density decreases with the increasing oxygen flow. By the tendencies of the relative intensities to N₂ (C³Πu→B³Π_g 1-0), the concentrations of the total produced O, H, and N₂⁺ are shown to increase with the oxygen flow. Based on the reactions for the production of H and O without and with the addition of O₂, the analytic solutions for H and O production are derived in accordance with the experimental results.