In this paper, a two-dimensional axisymmetric fluid model was established to investigate the influence of nitrogen impurity content on the discharge pattern and the relevant discharge characteristics in an atmosphere ...In this paper, a two-dimensional axisymmetric fluid model was established to investigate the influence of nitrogen impurity content on the discharge pattern and the relevant discharge characteristics in an atmosphere pressure helium dielectric barrier discharge(DBD). The results indicated that when the nitrogen content was increased from 1 to 100 ppm, the discharge pattern evolved from a concentric-ring pattern into a uniform pattern, and then returned to the concentricring pattern. In this process, the discharge mode at the current peak moment transformed from glow mode into Townsend mode, and then returned to glow mode. Further analyses revealed that with the increase of impurity level, the rate of Penning ionization at the pre-ionization stage increased at first and decreased afterwards, resulting in a similar evolution pattern of seed electron level. This evolution trend was believed to be resulted from the competition between the N2 partial pressure and the consumption rate of metastable species. Moreover, the discharge uniformity was found positively correlated with the spatial uniformity of seed electron density as well as the seed electron level. The reason for this correlation was explained by the reduction of radial electric field strength and the promotion of seed electron uniformity as pre-ionization level increases. The results obtained in this work may help better understand the pattern formation mechanism of atmospheric helium DBD under the variation of N2 impurity level, thereby providing a possible means of regulating the discharge performance in practical application scenarios.展开更多
Plasma-activated water(PAW)has been utilised in various application fields,and a deep understanding on the plasma chemistry is the foundation of application-orientated optimisation.In this paper,a global model is buil...Plasma-activated water(PAW)has been utilised in various application fields,and a deep understanding on the plasma chemistry is the foundation of application-orientated optimisation.In this paper,a global model is built to study the chemical properties of PAW produced by a dielectric barrier discharge that is powered by nanosecond voltage pulses.The applied voltage is firstly repeated with 10 kHz frequency for 100 s,and then shut down for 200 s afterglow,providing a long-term evolution regarding the production and consumption of some typical reactive oxygen/nitrogen species(RONS)in PAW.The calculated results agree principally with experimental measurements from literature.During the pulsed discharge,the water gradually acidises,and the long-lived species accumulate;while in the afterglow,most of the aqueous RONS decay rapidly,except for O_(3aq),NO_(3aq)^(−),H_(2)O_(2aq)and N_(2)O_(aq),which might be the main sources to sustain long-term effects.Furthermore,the effects of applied voltage and gap distance on RONS are investigated.Correlation analyses from Pearson correlation coefficient indicate that gaseous RONS are more sensitive to the gap distance,while the aqueous ones are more sensitive to the voltage amplitude,suggesting the possibility to independently regulating the gaseous and aqueous chemistry.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 51877086)
文摘In this paper, a two-dimensional axisymmetric fluid model was established to investigate the influence of nitrogen impurity content on the discharge pattern and the relevant discharge characteristics in an atmosphere pressure helium dielectric barrier discharge(DBD). The results indicated that when the nitrogen content was increased from 1 to 100 ppm, the discharge pattern evolved from a concentric-ring pattern into a uniform pattern, and then returned to the concentricring pattern. In this process, the discharge mode at the current peak moment transformed from glow mode into Townsend mode, and then returned to glow mode. Further analyses revealed that with the increase of impurity level, the rate of Penning ionization at the pre-ionization stage increased at first and decreased afterwards, resulting in a similar evolution pattern of seed electron level. This evolution trend was believed to be resulted from the competition between the N2 partial pressure and the consumption rate of metastable species. Moreover, the discharge uniformity was found positively correlated with the spatial uniformity of seed electron density as well as the seed electron level. The reason for this correlation was explained by the reduction of radial electric field strength and the promotion of seed electron uniformity as pre-ionization level increases. The results obtained in this work may help better understand the pattern formation mechanism of atmospheric helium DBD under the variation of N2 impurity level, thereby providing a possible means of regulating the discharge performance in practical application scenarios.
基金National Natural Science Foundation of China,Grant/Award Number:51977085。
文摘Plasma-activated water(PAW)has been utilised in various application fields,and a deep understanding on the plasma chemistry is the foundation of application-orientated optimisation.In this paper,a global model is built to study the chemical properties of PAW produced by a dielectric barrier discharge that is powered by nanosecond voltage pulses.The applied voltage is firstly repeated with 10 kHz frequency for 100 s,and then shut down for 200 s afterglow,providing a long-term evolution regarding the production and consumption of some typical reactive oxygen/nitrogen species(RONS)in PAW.The calculated results agree principally with experimental measurements from literature.During the pulsed discharge,the water gradually acidises,and the long-lived species accumulate;while in the afterglow,most of the aqueous RONS decay rapidly,except for O_(3aq),NO_(3aq)^(−),H_(2)O_(2aq)and N_(2)O_(aq),which might be the main sources to sustain long-term effects.Furthermore,the effects of applied voltage and gap distance on RONS are investigated.Correlation analyses from Pearson correlation coefficient indicate that gaseous RONS are more sensitive to the gap distance,while the aqueous ones are more sensitive to the voltage amplitude,suggesting the possibility to independently regulating the gaseous and aqueous chemistry.
