Measurements of N2(A) by pulsed cavity ringdown spectroscopy in repetitively pulsed nanosecond discharges

We present here results from the measurements of metastable N₂(A) species in nanosecond repetitively pulsed (NRPP) discharge in N₂ and air, obtained by using pulsed cavity ring-down spectroscopy (CRDS) at 770 nm. Despite the small plasma volume (1-10 mm³) and short lifetime of studied plasma species, CRDS enabled us to obtain spectra with spectral resolution down to 1 pm. The temporal variations of N₂(A) concentration in a nitrogen plasma were measured and absolute concentrations of N₂(A) in nitrogen and air plasmas were determined. These results were then used to validate a kinetic model, which already showed good agreement with the spatial and temporal evolution of other excited state species such as N₂(B), N₂(C), N₂ ⁺(B), NO(A) and O(3p ⁵P) measured using intensity calibrated emission spectroscopy.