Characteristics of atmospheric-pressure non-thermal N₂ and N₂/O₂ gas mixture plasma jet

An atmospheric-pressure non-thermal plasma jet driven by high frequency alternating current and operating on N₂ and N₂/O ₂ gas mixture is investigated. The plasma jet can reach 55 mm in length at a gas flow rate of 2500 l/h. The gas temperature at a distance of 4 mm from the nozzle is close to room temperature. Optical emission spectroscopy is employed to investigate the important plasma parameters such as the excited species, rotational temperature, vibrational temperature, and excitation temperature under different discharge conditions. The results show that the plasma source operates under non-equilibrium conditions. The absolute irradiance intensity of the vibrational band N₂(C-B) in the active region is measured. Taking into account the irradiance intensity of N₂(C-B,0-0) and N₂(B-X,0-0) as well as measured current, the electron density, which is determined by considering direct and step-wise electron impact excitation of nitrogen emission, reaches a maximum value of 5.6 × 10 ²⁰/m³.