Method for real-time measurement of nitrogen atom density in atmospheric pressure post-discharge flows

Abstract

A method has been developed for real-time measurement of nitrogen atom density in atmospheric pressure post-discharge flows. In this method, nitric oxide is supplied to the downstream of a nitrogen discharge as a reactant. Our chemical simulation has revealed that the injected nitric oxide is consumed mainly by reductive reaction with nitrogen atoms or oxidative reaction with oxygen atoms. The number density of atomic nitrogen is determined almost instantaneously through the measurement of nitric oxide and nitrogen dioxide densities with a gas analyser. The experimental verification was carried out with a dielectric barrier discharge unit as a nitrogen atom source, and the results showed good agreement with simulation predictions.

{\rm N}_2 \left({A\,^3\Sigma_{\rm u}^+} \right) behaviour in a N2–NO surface dielectric barrier discharge in the modulated ac regime at atmospheric pressure

“…However, such a density of highly vibrationally excited molecules would require a vibrational temperature of about 1500 K and the production of both N 2 X 1 + g , v 5 and N( 4 S) species should tend to be enhanced with increasing T ON . Nitrogen atom densities of up to 5 × 10 14 cm −3 were in fact reported in continuously excited atmospheric volume DBD and corona discharges in pure nitrogen [20][21][22]. However, it has been clearly shown that such [N( 4 S)] densities occur both in the Townsend and filamentary DBD regimes due to inefficient removal of nitrogen atoms through N + N + M recombination, which leads to accumulation of atomic species produced during successive discharge cycles.…”

Effect of Oxygen Impurity on Nitrogen Radicals in Post-Discharge Flows

“…Figure 1 shows the schematic diagram of the experimental setup used for the measurement of reaction products in the gases. It has a mixing point placed at downstream of a Nitrogen Radical Generator having the discharge chamber (13). The produced gases (N 2 O and O 3 ) reacted from the nitrogen radicals and the O 2 gas are measured by the Fourier Transform Infrared spectroscopy (FTIR).…”

“…This indicates the oxygen impurity in the supply gas did not affect the oxygen radical concentration at the measurement point. The concentration of nitrogen radicals generated by the Nitrogen Radical Generator was several ten ppm in the N 2 gas (13). The pressure in Nitrogen Radical Generator was varied from 30 to 120 kPa in the case of the N 2 flow rate at 5, 7, and 10 slm.…”

A comparative study of the surface recombination of nitrogen atoms on various materials at atmospheric pressure

“…To measure the nitrogen atom densities, the method described in [17] was adopted. This method is based on the fast reaction of N atoms with nitric oxide (NO), which enables measurements of N atom densities at the points of the NO mixture based on the following equation:…”

“…This indicates that the measured N atom densities are affected by the wall materials beyond the NO injection point. From comparisons of the two measurements, the NO mixing time was estimated to be about 1.5 ms. Other major causes of experimental error are the uncertainty attributed to the measurement method, which was estimated to be 10% at maximum [17], and the variation of the gas flow rates; this brings about 5 × 10 12 cm −3 of uncertainty to the measured densities.…”