Emission spectrometry for discharge plasma diagnosis

Emission spectrometry in the atmospheric pressure discharge was carried out to understand the reaction mechanisms of active species because the discharge plasma process is significantly affected by gas components. In this research, N2 second positive band and two band systems of NO such as NO-β band and NO-γ band were investigated by using a digital controlled spectrometer and an ICCD camera. When the dielectric pellets were placed on the needle-plate type electrode, emissions from both N2 second positive band and NO-γ band were reduced along the electrode axis. The emissionratio between N2 second positive band and NO-γ band was significantly different due to the existence of dielectric pellets. One dimensional analysis of emission spectral showed that NO-g band and N2 second positive band lay between the needle-plate electrodes, while emission spectral of NO-β band existed around the needle electrode. Two-dimensional analysis of the emission spectrum showed that NO-γ band and N2 second positive band exist between needle-plate electrodes. Observation by the time resolution of the emission spectrum showed that N2 second positive band emission was extinguished within 200 ns, while that from NO-γ band continued for more than 1 μs.