N2(A3Su+) behavior in N2 ¬NO surface dielectric barrier discharge under modulated AC regime at atmospheric pressure

Optical, electrical and discharge product measurements were performed in order to reveal the behaviour of N2(A 3+ u ) metastables in a surface dielectric barrier discharge (DBD) driven in N2 with small NO admixtures in a modulated ac regime. Metastable species were detected both in a thin surface plasma layer and in the space afterglow through plasma induced emission and optical-optical double resonance laser induced fluorescence, respectively. Basically, the observed N2(A 3+u ) species follow the discharge current oscillations in the plasma layer, while they evolve on a millisecond time scale due to diffusion through the space afterglow. Emission spectrometry provides a rough estimation of average metastable concentration in a thin surface plasma layer ~ 9 × 1013 cm-3. Fluorescence measurements then allow an upper estimation of metastable concentration in the space afterglow 1 × 1012 cm-3.