Measurement of N2(A 3Σ+u) metastable in N2 pulsed positive corona discharge with trace amounts of additives

The density of N2(A 3Σ+u) metastable is measured in various gases (N2/O2, N2/NO, N2/NO2, N2/H2O, N2/CO) after pulsed positive corona discharge using time-resolved laser-induced fluorescence (LIF) under atmospheric pressure. The N2(A 3Σ+u) density in N2/O2(0.25%) is uniformly distributed along the axis of the discharge gap (point-to-plane, 12 mm). This result indicates that N2(A 3Σ+u) is mostly generated in the primary streamer channels. The absolute N2(A 3Σ+u) density is measured by calibrating the LIF signal intensity. When the discharge voltage is 21.5 kV, the N2(A 3Σ+u) density immediately after the discharge pulse is estimated to be (2-3) x 1013 cm-3. The reaction rate constants of N2(A 3Σ+u) with O2, NO, NO2, H2O and CO are roughly estimated using the decay rate of N2(A 3Σ+u) density after the discharge pulse, and are compared with reference values. N2(A 3Σ+u) production is increased approximately twofold when hundreds of ppm of O2, NO or NO2 molecules are added to N2.