Study On The Process And Characteristics Of Atmospheric Pulse And AC Coupling Discharge

Atmospheric pressure plasma is a new plasma generation technology in recent years,which has the advantages of flexible and simple operation and good controllability,among which atmospheric pressure plasma jet shows great application prospect.Traditionally,the plasma jet is generated by alternating voltage excitation with repetition frequency in the range of kilohertz,and two discharges are generated at the rising edge of the positive and negative half periods of alternating sinusoidal voltage.The plasma jet excited by pulse voltage has higher electron generation efficiency and electron density than the plasma jet excited by ac voltage,and the voltage rising along time is on the order of nanosecond.At present,most atmospheric plasma jets are generated under AC or pulse excitation,and the jet characteristics are closely related to the electrical characteristics of the excitation source.Therefore,it is of great value to study the coupling relationship between different excitation sources to develop the application of atmospheric pressure plasma jet.In this paper,plasma jet is generated by pulsed discharge coupled with AC sinusoidal discharge,and the influence of their interaction on the generation and propagation of plasma jet is studied.Firstly,plasma jet is generated by ac sinusoidal voltage assisted pulse discharge,and the effects of different phases of ac sinusoidal voltage on plasma jet characteristics and discharge process are studied.The propagation of plasma jet in the form of plasma bullet in the discharge space is characterized by the evolution of non-thermal distribution in the pulse voltage stage.Under the condition of fixed AC sinusoidal voltage,the generation time of pulse voltage is adjusted by delay,so that it is at the time of 50 ?s,100 ?s and 150 ?s,respectively.Under the condition of fixed AC sinusoidal voltage,the generation time of pulse voltage is adjusted by delay,so that it is at the time of 50 ?s,100 ?s and 150 ?s respectively.On the contrary,when the polarity of pulse voltage is opposite to that of ac sinusoidal voltage,the generation of plasma bullet will be strengthened and the propagation speed will increase.The dynamic process of plasma bullet generated by pulse discharge is studied by the time evolution of the intensity of discharge image and the spatial distribution of the velocity of plasma bullet.In addition,the interaction between pulse discharge and AC discharge and the characteristics of the coupling discharge as well as the discharge process are studied by measuring the current and voltage waveform and the space-time distribution image of plasma discharge.By comparing the effects of different pulse voltages and different pulse voltages on the temporal and spatial evolution of plasma bullets,the time when ac discharge occurs and the polarity of discharge current are revealed.When the polarity is opposite,the plasma jet generated by pulse discharge is enhanced,and when the pulse voltage pulse width is small,the influence of AC discharge is more significant.