Investigation of spatially resolved spectra of OH and N2+ in N2 and H2O mixture wire-plate positive pulsed streamer discharge

Optical emission spectroscopy has been applied to study the spatially resolved measurements of the emission intensities of OH (A2Σ → X2Π, 0–0) and N2+ (B2Σu+ → X2Σg+, 0–0, 391.4 nm) produced by a high-voltage positive pulsed streamer discharge consisting of a gas mixture of N2 and H2O in a wire-plate reactor under severe electromagnetic interference at atmospheric pressure. The effects of pulse peak voltage, pulse repetition rate, and the added O2 flow rate on the spatial distributions of the emission intensity of OH (A2Σ → X2Π, 0–0) and N2+ (B2Σu+ → X2Σg+, 0–0, 391.4 nm) in the lengthwise direction (direction from wire to plate) are investigated. It has been found that the emission intensities of OH (A2Σ → X2Π, 0–0) and N2+ (B2Σu+ → X2Σg+, 0–0, 391.4 nm) rise with an increase in both pulse peak voltage and pulse repetition rate and decrease with an increase in oxygen flows added in an N2 and H2O gas mixture. The emission intensity of OH (A2Σ → X2Π, 0–0) decreases with increasing the distance from the wire electrode. The emission intensity of N2+ (B2Σu+ → X2Σg+, 0–0, 391.4 nm) is nearly constant at 0–4 mm from wire electrode, and sharply increases near the ground electrode. The vibrational temperature of N2 (C) increases with increasing O2 flows and keeps almost constant in the lengthwise direction under the present experimental conditions. The main physicochemical processes involved are also discussed in this paper.