Study of hydroxyl radical (A,0) generated in DBD at ambient pressure with power supply frequency 50 Hz

• OH Emission at 3090 Å observed only in air/argon plasma, absent in pure air plasma. • Gas Temperature reached 420 ± 10 K at 11.6 kV, with OH intensity peaking at 0.3 cm gap. • Electron Density & Power estimated at ∼10¹⁷ m⁻³ and 6.2 W, confirming efficient plasma generation. The light emitted spectra of air and air/argon plasmas at ambient pressure in a dielectric barrier discharge (DBD) operating at power supply frequency, 50 Hz, were recorded using an optical emission spectrometer (OES). The spectra cover the full wavelength range from 2000 A 0 to 11000 A 0 . It was found that air/argon plasma displays the radical composed of OH (A²Σ⁺(v′=0) → X²Π(v″=0)) at 3090 A 0 , a feature not observed in air plasma. The LIFBASE software suite was utilized to obtain the best fit between simulated and experimental spectra. At a voltage amplitude of 11.6 kV and a discharge gap of 0.3 cm, the plasma gas temperature, determined from the OH (3090 A 0 ) line, was found to be 420 ± 10 K. Additionally, the intensity of the OH radical (3090A 0 ) in air/argon plasma was studied in relation to the argon gas flow rate, applied voltage, and discharge gap. The results showed that, at a constant discharge gap, the OH intensity increases with higher argon flow and applied voltage. However, as the discharge gap increases, the OH intensity first rises and then decreases. The maximum OH intensity for a given applied voltage occurs at a discharge gap of 0.3 cm. Furthermore, the electrical diagnostics of air/argon plasma were done. Using the current density method, the electron concentration was found to be around 10 17 m -3 . Analysis of the current and voltage waveforms, along with the Lissajous figure approach, indicated that the reactor's power consumption was 6.2 watts. These findings contribute to a better understanding of DBD plasma's physical and chemical properties, and its potential applications in fields such as plasma agriculture, plasma chemistry and plasma medicine.