Spatial Distribution of Light Emission in Microplasma under 100 µm Gaps

Abstract

Emission spectroscopy analysis was used to study the microplasma phenomena. The microplasma discharge in Ar, N2/Ar, and O2/Ar was analyzed in the discharge gap area, and the spatial distribution of active species was also measured outside the electrodes. The spatial distribution in the discharge gap showed a higher intensity of the N2 second positive band system (N2 SPS) peak towards the grounded electrode (anode). The measurement of OH peak at 308.9 nm proved the existence of this excited species 1 mm outside the electrodes area. Images of the discharges at various gaps showed that the diameter of streamers derived from microdischarges was about 10 µm at the 100 µm gap, then decreased relative to the decrease in gap width. For gas mixtures containing N2 in Ar, a more diffuse discharge was observed with the decrease in the amount of N2 in Ar. The results are necessary for optimizing microplasma processes such as surface treatment and biomedical applications.