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In this paper, the mechanisms of light emissions, including NO-γ, NO-β and N2-SPS, produced in a N2/NH3 atmospheric-pressure dielectric barrier discharge considering realistic oxygen impurity (30 ppm) are investigated numerically and experimentally. Self-consistent, one-dimensional fluid modeling is used to numerically simulate the discharge process with 48 species and 235 reaction channels. An optical emission spectrometer (OES) is used to measure the relative intensities of the light emission. The simulations of the light emission intensities for the above-mentioned OES lines generally reproduce the trends observed in the experiments caused by changes in the NH3 concentration. All of the predicted intensities of NO-γ, NO-β and N2-SPS decrease with increasing amount of NH3 caused by various reaction mechanisms. The former is due to the loss of N2(A) and NO(A) by the reaction of NH3 with N2(A) and NO(A), respectively. The decrease in NO-β is due to the depletion of N and O because of NH3, and the decrease in N2-SPS is due to electron attachment to NH3 and a weaker metastable–metastable associative ionization of N2. All of the simulated results demonstrate that the discharges are typically Townsend-like because the ions outnumber the electrons and the electric field across the gap is distorted only slightly by the charged particles during the breakdown. Finally, a reduced chemical kinetics model for a planar atmospheric-pressure N2/O2/NH3 dielectric barrier discharge is proposed and validated by benchmarking against the above complete chemical kinetics. This results in a reduced chemical kinetics consisting of 33 species and 87 reactions with a very limited loss of accuracy of discharge properties, while it is 2.1 times faster in computational time as compared with the complete version. [ABSTRACT FROM AUTHOR]

In this paper, a planar atmospheric-pressure dielectric barrier discharge (AP-DBD) of nitrogen mixed with ammonia (0-2 %) is simulated using one-dimensional self-consistent fluid modeling with cell-centered finite-volume method. This AP-DBD is driven by a 30 kHz power source with distorted sinusoidal voltages. The simulated discharge current densities are found to be in good agreement with the experiment data in both phase and magnitude. The simulated results show that the discharges of N mixed with NH (0-2 %) are all typical Townsend-like discharges because the ions always outnumber the electrons very much which leads to no quasi-neutral region in the gap throughout the cycle. N and N are found to be the most abundant charged species during and after the breakdown process, respectively, like a pure nitrogen DBD. NH increases rapidly initially with increasing addition of NH and levels off eventually. In addition, N is the most dominant neutral species, except the background species, N and NH, and NH and H are the second dominant species, which increase with increasing added NH. The existence of abundant NH plays an important role in those applications which require functional group incorporation. [ABSTRACT FROM AUTHOR]

The non-equilibrium atmospheric-pressure parallel-plate helium dielectric barrier discharge (DBD) driven by a realistic 20 kHz distorted-sinusoidal voltage waveform has been investigated by means of simulations and experiments. A self-consistent one-dimensional fluid modeling code considering the non-local electron energy balance was applied to simulate the helium DBD. The effect of selecting plasma chemistry was investigated by comparing simulations with experiments. The results show that the simulations, which include more excited helium, metastable helium and electron-ion-related reaction channels, can faithfully reproduce the measured discharged temporal current quantitatively. Based on the simulated discharge properties, we have found that there is complicated mode transition of discharges from the long Townsend-like to the 'dark current'-like, then to the short primary Townsend-like and the short secondary Townsend-like for the helium DBD that is driven by a realistic distorted-sinusoidal voltage power source. Discharge properties in different periods of discharge are discussed in detail in the paper. [ABSTRACT FROM AUTHOR]