Decrease in dinitrogen monoxide (N2O) generation of air-fed ozone generator using Atmospheric Pressure Townsend Discharge

Summary form only given. Ozone is strong oxidizing agent and it can be applied to air quality control, waste water treatment, etc. So far, we succeeded in generating an Atmospheric Pressure Townsend Discharge (APTD) in air using a simple DBD device and have investigated the difference of the by-products of ozone by the difference of discharge modes. Ozone generation experiments were carried out using APTD and Filamentary Discharge (FD) modes by feeding dry-air. The experimental results showed that in both types of discharges, HNO₃, N₂O₅ and N₂O were detected as by-products, however the amount of the by-products by APTD was less than by FD. Since the reduced electrical field of the APTD is lower than that at the tip of streamer heads of FD, the dissociation and excitation of nitrogen molecules and water vapor were weak in APTD. This is a reason that NOx generation was suppressed by APTD. In this study, we investigated the effect of gap length on ozone and N₂O generation characteristics because the reduced electric field strength of APTD can be changed by changing gap length. Dry-air (absolute humidity: 119.3 mg/m₃) was used as the source gas of APTD ozone generator. The flow rate was fixed to 2.0 L/min using a mass flow controller. Gap length was changed from 1.1 mm to 3.1 mm. The barrier material is alumina (Type: A473, Kyocera Corporation). The amount of ozone was measured by changing the discharge power. N₂O concentration was measured by an FTIR spectrometer with long path gas cell (length: 3 m). On the other hand, ozone concentration was measured by a UV absorption type ozone monitor. The results showed that at the same ozone concentration, the N₂O concentration decreased with the increase of gap length, which support our idea that the reduced electric field strength will influence the by-product generation.