Spectrum Diagnosis Of Ar/N₂/H₂O Plasma With Coaxial Surface Dielectric Barrier Discharge

In order to study the microscopic mechanism of surface dielectric barrier discharge under low pressure,we diagnose Ar plasma,Ar/N₂plasma and Ar/H₂O plasma by using tunable diode absorption spectroscopy(TDLAS)and emission spectroscopy(OES)in this paper.The number density and gas temperature of Ar metastable atom were measured by absorption spectroscopy,meanwhile the electronic excitation temperature and the rotational temperature of N₂and OH radical were measured by emission spectroscopy.The effects of discharge voltage,discharge frequency,gas pressure,gas flow rate and some discharge parameters on the metastable number density of argon,gas temperature and rotation temperature are also studied.The experimental results obtained are as follows:1)When using tunable diode absorption spectroscopy to measure the metastable number density of argon,it is found that with the increase of the discharge voltage and gas flow,the metastable density of 1s₅and 1s₃state increases;With the change of gas pressure,the extreme value appears:With the increase of pressure,the number indensity of argon 1s₅and 1s₃firstly increase in the range of 0.35-0.7 k Pa,the decrease in the range of 0.7-1.4 k Pa.2)A spectrometer was used to measure the emission spectrum of argon plasma in the range of 600-850nm,and the Boltzmann slope method was used to calculate the characteristic spectral lines with strong light intensity.The experimental results found that with the increase of voltage and frequency,the electronic excitation temperature increases;as the pressure increases,the temperature decreases.3)The spectral lines of the second positive band system of N₂(C³?u?B³?g)in Ar/N₂plasma at 337 nm were diagnosed by emission spectrum,and the spectral intensity measured by the experiment was compared and analyzed with the spectral line intensity simulated by Specair software,and the rotation temperature of nitrogen was measured.The experimental results show that the rotational temperature increases with the increase of discharge voltage and frequency.As the pressure goes up,the rotational temperature goes down.4)By carrying water vapor in argon gas,the emission spectrum of OH radicals was diagnosed,and the OH radical spectral profile was fitted by using Lifbase software to calculate the rotational temperature of the OH radicals around 1000K.