Laser-induced fluorescence of N2() metastable in N2 pulsed positive corona discharge

Abstract

The density of N2() metastable is measured in N2 pulsed positive corona discharge using time-resolved laser-induced fluorescence (LIF) under atmospheric pressure. The N2(, v″ = 0) state is excited to N2(B 3Πg, v″ = 4), then the fluorescence from the (B 3Πg, v″ = 4) to (, v″ = 1) band is measured. The discharge occurs in a 12 mm point-to-plane gap. The good agreement between the measured and theoretical LIF excitation spectra shows that the LIF measurement of N2() in the pulsed corona discharge is correctly performed. The decay curve of the N2() density after discharge cannot be fitted to a single exponential. This indicates that the density of N2() metastables mainly decreases by the pooling reaction, , where is electronically excited N2. When the discharge voltage is 22 kV, the N2() density immediately after discharge is estimated to be less than 6 × 1013 cm−3 at the midpoint of the 12 mm discharge gap.