The non-equilibrium atmospheric-pressure parallel-plate helium dielectric barrier discharge (DBD) driven by a realistic 20kHz
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.
[Show abstract][Hide abstract] ABSTRACT: In this paper, a planar atmospheric-pressure dielectric barrier discharge (AP-DBD) of nitrogen mixed with ammonia (0textendash2 %) 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 2 mixed with NH 3 (0textendash2 %) 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 2 + and N 4 + are found to be the most abundant charged species during and after the breakdown process, respectively, like a pure nitrogen DBD. NH 4 + increases rapidly initially with increasing addition of NH 3 and levels off eventually. In addition, N is the most dominant neutral species, except the background species, N 2 and NH 3 , and NH 2 and H are the second dominant species, which increase with increasing added NH 3 . The existence of abundant NH 2 plays an important role in those applications which require functional group incorporation.
[Show abstract][Hide abstract] ABSTRACT: In this study, we present a temporal multi-scale algorithm (TMA) for efficient fluid modeling of a one-dimensional gas discharge with complex plasma chemistry. A helium dielectric barrier discharge driven by a power source with a frequency of 25 kHz is used as an example to demonstrate the superior capability of the TMA in accelerating fluid modeling simulations, while maintaining the same accuracy as compared to lengthy benchmarking fluid modeling using a single time-scale approach. The plasma chemistry considers 36 species and 121 reaction channels, which include some impurities such as nitrogen (25 ppm), oxygen (10 ppm) and water vapor (1 ppm), in addition to the helium itself. The results show that the runtime using the TMA can be dramatically reduced to 4% (25 times faster) with a relative difference of spatially averaged number densities generally less than 1% for all species between the TMA and the benchmarking cases when five initial cycles, five supplementary cycles and four repeated stages are used. Further reduction of the accuracy requirements to 44% for some specific species can lead to 92 times faster performance with the use of two initial cycles, two supplementary cycles and two repeated stages. The outlook for multi-dimensional fluid modeling considering a gas flow field is also described at the end of the paper.
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