Ar Spectroscopic Diagnosis Of Ar/He/N₂ Dielectric Barrier Discharge Plasma

Dielectric Barrier Discharge?DBD?has been widely studied and applied in many fields due to its simple experimental device and easy realization of uniform and stable discharge.However,due to the complicated discharge process and mutual physical and chemical reactions,the research of DBD is not mature compared to its wide application.In recent years,there is an upsurge in the study of plasma discharges of rare gases,such as helium,neon,and argon.There are a large number of metastable states with long life and high energy in the plasma discharge of Ar,which is an effective energy transfer carrier in the process of discharge plasma.By mixing two or more gases,some energy transfer processes in discharge plasma can be studied.Especially in the fields of plasma chemistry,the changes of gas composition,ratio,discharge parameters and so on have an important influence on the physical and chemical reaction of the plasma and the optimization of the reaction process,among which the energy transfer process is particular critical.In this paper,argon,helium,and nitrogen are mixed to explore the effects of different conditions on the metastable density,gas temperature,electron density,and electron temperature in low-pressure Ar DBD.The absorption spectrum diagnosis device and emission spectrum diagnosis device are used to study the effects of discharge conditions and gas contents on some plasma parameters of Ar/He/N₂ dielectric barrier discharge.The results are listed as follows:?1?Based on absorption spectroscopy and Lambert-Beer law,quantitative change of number density for Ar metastable 1s₃ and 1s₅ under different gas ratios and discharge conditions is calculated.It is found that the 1s₅ number density is 5 to 12 times that of the 1s₃,and the number density decrease as the concentration of He and N₂ increases.The increased pressure,gas flow rate and discharge voltage can also cause the metastable density to increase,but till a certain value of pressure,the increase in the metastable density slows down,with bigger pressure the number turns to decrease.?2?The gas temperature in the discharge is measured according to the Doppler broadening effects.It was found that under experimental conditions,the gas temperature decreases as the concentration of He increases but increases as other discharge conditions increase.The gas temperature of the mixed gas is lower than that of pure Ar.?3?Based on emission spectroscopy measurement,the electron temperature is calculated by the Boltzmann slope method and the Corona model.It is found that the electron temperature increases with the increase of He content,N₂ content and voltage,and decreases with the increase of pressure and gas flow in the reaction chamber.The tendency of electron density with discharge conditions is analyzed according to the Corona model.It is found that the electron density decreases with the increase of He content,N₂ content and voltage,and increases with the increase of pressure and total gas flow in the reaction chamber.