| Atmospheric dielectric barrier discharge(ADBD),as an effective means to generate lowtemperature plasma under atmospheric pressure,has attracted wide attention in many application fields.Generally,in ADBD,only one current pulse generates in each applied voltage half cycle,showing a single-current-pulse(SCP)behavior.However,under certain conditions,two or more current pulses will appear in each applied voltage half cycle,which shows a multiple-current-pulse(MCP)behavior.Relevant studies have shown that,compared with the SCP mode,the appearance of MCP behavior is usually accompanied by unstable discharge and a decrease in energy efficiency,which is not conducive to practical applications.Therefore,understanding the evolution mechanism and the manipulation of MCP behavior is of great importance to the improvements of discharge stability and energy efficiency in ADBD applications,but in previous studies,the evolution mechanism of MCP behavior has not been fully clarified,and there is a lack of research on the manipulation of MCP behavior.Combining with actual application scenarios,this paper establishes a one-dimensional fluid model of helium ADBD containing trace amount(0-10000 ppm)of air,and the experiments of helium/air ADBD was carried out.The validity of the model is verified by comparing the simulation and experimental results under the same conditions.On this basis,the evolution mechanism and manipulation of MCP behavior in helium/air ADBD is investigated,the main content are as follows:(1)The simulation and experiment of helium ADBD under different air contents were carried out.The simulation and experimental results both show that with the increase of air content,the discharge mode changes from single-current-pulse mode to multiple-current-pulse mode.By analyzing the variation of the current component in the simulation results,it is concluded that the conversion of single/multi-pulse mode is caused by the change of the variation rate of gap voltage.By analyzing the variation of reaction rate in the simulation results,it is concluded that the special oxygen attachment reaction in helium/air ADBD can inhibit the appearance of multi-pulse behavior.(2)The sinusoidal drive was replaced by harmonic modulation in the simulation model.The simulation results show that the harmonic modulation can effectively regulate the multipulse mode without affecting the content of reactive species,and realize the independent control between the multi-pulse behavior and the content of reactive species.In addition,the higher the harmonic content,the higher the electron generation rate.The results show that the variation of gap breakdown voltage and discharge current amplitude under different harmonic content are related to the variation of discharge spatial structure and surface charge of dielectrics.(3)Harmonic modulation,harmonic content and single pulse discharge mode are used as manipulation methods,control parameters and control targets.With the help of the correlation between single pulse mode,key discharge parameters,and control parameters,the parameter range corresponding to SCP mode is estimated and calculated.The calculation results are in good agreement with the simulation results,verifying the effectiveness of the estimation method. |
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