Optical Emission Spectroscopy Study For The Surface Dielectric Barrier Discharge At Atmospheric Pressure

The Surface Dielectric Barrier Discharge at Atmospheric Pressure has been investigated by optical emission spectroscopy(OES) in this paper. Electron excitation temperature, molecular vibrational temperature and gas temperature were examined in Ar, N2/Ar, O2/Ar and O2/N2/Ar discharges, respectively, and also a qualitative analysis was made to optimize the atomic oxygen concentration in O2/Ar and O2/N2/Ar discharges.Ar atom excitation temperature was obtained by using the Boltzmann-plot method in Ar discharge, and its evolution with the flow rate and input voltage was also studied, which indicated that Ar atom excitation temperature increased with increasing input voltage and varies irregularly with different flow rates. the spectrum of OH was recorded during the discharge due to the trace water in Ar, and the evolution of gas temperature with discharge parameters was examined by fitting the rotational temperature of OH A state. The result shows, within our experimental condition, gas temperature is approximately 450 K in Ar discharge and exhibits little dependence on the flow rate and input voltage.In Ar/N2 discharge,the effect of N2 content on the dicharge was specially examined, and four sequential band groups (Δv=-1,Δv=-2,Δv=-3,Δv=-4) of N2 C3Πu- B3Πg were choosed to estimate the vibrational temperature of N2 C. The intensity of Ar emission lines decreased greatly with a small amount of N2 (about 1%) added to Ar while that of N2 emission lines increased substantially. With the increasing content of N2 from 0.1%to 5%, the electron excitation temperature increased from 4500 K to 6000 K, in contrast, the molecular vibrational temperature decreased from 2300 K to 1800 K.Optimization of atomic oxygen concentration was in particular discussed in 02/Ar and O2/N2/Ar discharges, respectively. The evolution of atomic oxygen concentration with the varying O2 content was studied by the emission intensity ratio (I844.6/I750.4) of Ar and O atom. The result demonstrated that when the atomic oxygen content in feed gas reached up to approximately 0.15%, atomic oxygen concentration increased to a peak value, and then decreased slowly with further increase of O2 flow rate.In addition, the evolution of atomic Ar excitation temperature with input voltage was also investigated in O2/Ar and O2/N2/Ar discharges, respectively, and their excitation temperature both increased with increasing input voltage.