Study On Two Different Hyper Hexagonal Patterns And Spectral Diagnosis In Dielectric Barrier Discharge

Two novel self-organizing pattern are observed in dual-water electrode AC gas dielectric barrier discharge system for the first time,namely the triangular lattice pattern with invisible Kagome lattice and the snowflake pattern.The spatiotemporal dynamics and formation mechanism of the patterns are studied by means of electrical measurement and optical diagnosis with digital oscilloscope,photomultiplier tubes?PMTs?,intensified charge-coupled device?ICCD?,spectrometer and other equipment.The study found that the two self-organizing patterns are the result of the interaction between volume discharge?VD?and surface discharge?SD?,and the surface charges play a very important role in the formation of the patterns;in addition,the influence of gas composition and discharge spacing on plasma parameters is investigated by means of spectral diagnosis by redesigning the discharge cell.The main research contents and results are as follows:?i?A novel pattern named triangular lattice pattern with invisible Kagome lattice is observed in dielectric barrier discharge system with two water electrodes for the first time.The spatiotemporal dynamics studied by an intensified charge-coupled device?ICCD?show that the complex pattern is composed of four different sublattices:Kagome lattice,halos,and big and small spots?B and S?.The invisible Kagome lattice is similar to the dark discharge because of its spatiotemporal randomness.Based on the novel discharges?B and S?occurring at the falling edge of applied voltage,the dynamics of surface charges is investigated and demonstrated with a high speed video camera and photomultiplier tubes.Furthermore,the formation of restricted random structures is considered to be the effect of previous discharges which rearrange the surface charges.?ii?The snowflake pattern which consists of bright spots and dim lines is investigated in a dielectric barrier discharge system.Visually,dim lines straightforwardly converge to the center of three bright spots.The spatiotemporal dynamics shows that the bright spots are formed by the volume discharges?VDs?,and the dim lines are formed by the surface discharges?SDs?.The snowflake pattern is the result of VD induced SD and SD transfer surface charges.The emission spectra of the N₂ second positive band?C³?_u?B³?_u?and the spectral lines of Ar I?2P₂?1S₅?of VD and SD are collected and analyzed,respectively.It is found that the ratio values of emission intensity of VD to SD at 696.5 nm and 380.4 nm are 4.4 and 1.3,respectively.It indicates that the number of electrons that can excite Ar and N₂ to emit the optical spectrum in VD is more than that of SD.A new method of differentiating VD and SD is suggested.?iii?The plasma parameters are closely related to the discharge configuration in the dielectric barrier discharge system.In order to investigate the influence of the gas composition and the discharge spacing on the plasma parameters,the diagnosis of different plasmas under identical conditions is required.In this experiment,the discharge cell is a flat multiplicate gas gap,which is composed of three thickness of 1.2 mm square glass frames with the discharge area side length as 40 mm,30 mm and 20 mm respectively.The emission spectra of the N2second positive band?C3?u?B3?u?of the three filaments are collected in the experiment by spectrograph.The molecule vibration temperatures are calculated based on emission intensity;based on the relative intensity of the N₂⁺line at 391.4 nm and the N₂ line at 394.1 nm,the electron average energy of the three kinds filaments are investigated.The changing trends of molecular vibration temperature and electron average energy are obtained by changing the Ar content.This paper has important reference significance for studying plasma parameters and industrial production in DBD system.