Characteristics of atmospheric Ar/NH3 DBD and its comparison with He/N2 DBD.

The discharge mode and photoelectric characteristics of Ar/NH₃ DBD (dielectric barrier discharge) are studied to discuss the stability of the discharge under the influence of Penning ionization and attachment reaction. There are three discharge modes, including stable uniform glow discharge, unstable glow discharge and unstable columnar discharge. Discharge instability, including nonuniform discharge and discharge channel split, occurs under low (<0.10%) or high (>0.35%) volume fractions of NH₃, which are understood to be caused by an insufficiently strong Penning effect or a strong attachment reaction, respectively. The attachment reaction of NH₃ can also lead to a weaker emission intensity for Ar/NH₃ DBD, in particular regarding the emission of OH(A²Σ⁺). Ar/NH₃ and He/N₂ DBDs are also compared. In He/N₂ DBD, the emission intensity of OH(A²Σ⁺) changes less with increasing N₂ volume fraction, which may be attributed to the lack of attachment reaction. Compared with Ar/NH₃ DBD, the single discharge channel in He/N₂ DBD is narrower, but the discharge area is wider, which should be induced by the higher Townsend ionization coefficient nonlinearity of He/N₂ and the absence of attachment reaction in He/N₂, respectively. In the end, a one-dimensional fluid model of Ar/NH₃ DBD is built to verify the explanation of experimental results. [ABSTRACT FROM AUTHOR]