Determination of N-atom Density in High Ar- N\(_2\) Gas Pressure Microwave Afterglow

Abstract

This chapter is devoted to the production of N-atoms and other N₂ active species in Ar₂ - N₂ flowing afterglows of microwave discharges at high gas pressure from 100 to 760 Torr (atmospheric gas pressure). The determination of N -atoms density in high-pressure Ar-N₂ microwave afterglow is revisited. First, it is observed that pure pink afterglows are mainly obtained at high pressures up to atmospheric gas pressure, which is an a_N+N factor of N+N recombination near 0. Second, there is an uncertainty in the range k=10^-11-10^-12cm³ s^-1 on the k-rate coefficient of the reaction N₂,v>13+N₂(A) \(\rightarrow\) N₂(B,v')+N₂ which dominates the pink afterglow An enhancement of the N₂(B,v'=8)/N₂(B,11) density ratio is observed up to the atmospheric gas pressure. It was interpreted by a reduction of the quenching of the N₂(B,v'=8) by Ar. Values of the N+N recombination rates were determined when a_N+N>0.1. It was found a large uncertainty depending on the N₂(B,v'=11) quenching rates found in the literature. It is estimated a decrease in the N+N recombination rates by 0.6 in the Ar-2% N₂ in comparison to pure N₂ afterglow. The determination of N-atoms density in high-pressure Ar- xN₂ microwave afterglow is revisited. First, it is confirmed that pure pink afterglows are mainly observed at high pressures up to atmospheric gas pressure when x <10%, that is aN+N < 0.1.