Characteristics Of Ionization Wave In Nanosecond-pulse Surface Dielectric Barrier Discharges

Recently,various forms of flow control methods have been widely concerned by researchers due to the wide application prospect of plasma flow control technology in the field of aerospace.The surface dielectric barrier discharge(SDBD)actuator is of great practical value due to its simple structure,high response efficiency and high response speed.During SDBD discharge,plasma propagates forward in the form of surface ionization wave(SIW),and its propagation characteristics are affected by many factors.Under the premise that plasma diagnosis technology is limited,the study of its propagation characteristics is helpful to analyze its specific physical process Therefore,in this paper,a nanosecond pulsed generator for surface dielectric barrier discharge was developed for the application requirements of surface dielectric barrier discharge,and the propagation characteristics of surface ionization waves were studied.Firstly,a high voltage nanosecond pulsed generator based on a fast-solid-state switch is constructed by switching on and off the fast-solid-switch.The switch used is the high-current switch produced by BEHLKE company in Germany.According to its control principle,Altium Designer Software is used to design the low-voltage control circuit and the main circuit.Then,its topology structure is designed and boxed,and its output characteristics are tested.The test results show that the output voltage amplitude of the nanosecond pulse power supply is adjustable from 0?20 k V,the repetition frequency is adjustable from 0-5 k Hz,the pulse width is adjustable from 200 ns?500 ns,and the rising and falling edge are both 15 ns.The output waveform of power supply is stable,which can run stably for a long time.At the same time,the power supply has the following advantages: small size,light weight and easy to handle.Surface dielectric barrier discharge actuators with multi-ground electrode array structure were fabricated with PTFE and ER as dielectric materials respectively.The voltage and current test results show that two breakdown occurred in the rising edge of the pulse voltage,and the discharge channel was formed,which were primary ionization wave and secondary ionization wave respectively.The higher the pulse repetition frequency is,the faster the current attenuation rate of SIW is,while the propagation speed of SIW changes little.The higher the pulse voltage amplitude is,the faster the propagation speed of SIW is,and the current attenuation rate of SIW is basically not affected.The electric field test results show that the electric field peak value is larger in epoxy resin medium which reaches 30 k V/cm,and the spatial attenuation of the peak value along the propagation direction of the surface ionization wave is smaller.The repetition frequency only affects the remaining electric field of PTFE medium,that is,the magnitude of the absolute value of the remaining electric field increases with the increase of the repetition frequency.In addition,the electric field time evolution under different pulse repetition frequencies is basically the same.The experiment proves that the electric field generated by the surface residual charge in SDBD is opposite to that generated by the surface ionizing wave,that is,the surface residual charge inhibits the surface ionizing wave propagation and the discharge energy injection process.This conclusion is helpful to improve the energy coupling efficiency of SDBD in practical application.