Plasma Chemistry in an Atmospheric Pressure Ar/NH₃ Dielectric Barrier Discharge

Abstract

Abstract Summary: An atmospheric pressure dielectric barrier discharge (DBD) in Ar/NH 3 (0.1–10%) mixtures with a parallel plate electrode geometry was studied. The plasma was investigated by emission and absorption spectroscopy in the UV spectral range. Discharge current and voltage were measured as well. UV absorption spectroscopy was also employed for the detection of stable products in the exhaust gas. To clarify the different processes for ammonia decomposition, N 2 (2–10%) was added to the plasma. Modeling of the chemical kinetics in an Ar/NH 3 plasma was performed as well. The dominant stable products of an atmospheric pressure Ar/NH 3 DBD are H 2 , N 2 and N 2 H 4 . The hydrazine (N 2 H 4 ) concentration in the plasma and in the exhaust gases at various ammonia concentrations and different discharge powers was measured. Thermal N 2 H 4 decomposition into NH 2 radicals may be used for NO x reduction processes. The differences in the optical emission spectra of NH radicals formed in Ar/NH 3 plasma with various ammonia concentrations (0.7, 2, and 10%) were associated with different excitation mechanisms of NH radicals. magnified image The differences in the optical emission spectra of NH radicals formed in Ar/NH 3 plasma with various ammonia concentrations (0.7, 2, and 10%) were associated with different excitation mechanisms of NH radicals.