Investigation on the spatial distribution of active species in atmospheric-pressure plasma jet using optical emission spectroscopy and fluid simulation

Summary form only given. An atmospheric-pressure plasma jet (APPJ) based on dielectric barrier discharge was manufactured to analyze its discharge characteristics. The APPJ was driven by 50 kHz sinusoidal waveform having peak-to-peak voltage 3-4 kV and He or Ar was used for working gases. In the APPJ system, the active species generated in the plasma such as electrons, ions, and radicals are transported along the flow channel. Thus, the density of these species has a strong spatial dependence because of admixture with air in plasma channel.¹ In this study, discharge characteristics were investigated by using optical emission spectroscopy. Different optical emission distributions were observed according to plasma conditions such as working gas, gas flow rate, and input voltage. For Ar plasma, OH and N₂ related emission lines were detected higher than those in He plasma. On the other hand, relatively strong emission lines of N₂⁺ and O excited species were detected in He plasma case. These results are caused by difference of energy level to generate ions or metastable species in each plasmas. Especially, metastable He atom plays an important role in downstream plasma region. Also, the APPJ was investigated by using axis-symmetry 2D fluid simulation and compared with the experimental results. The effects of working gas-air mixture in the downstream region were modeled with binary diffusion and Navier-Stokes equation.