Influence of electrode geometry on the transport of OH radicals in an atmospheric pressure surface micro-discharge

Atmospheric pressure surface micro-discharge (SMD) has recently received considerable interest as an efficient source for its potential applications in biomedical, agricultural and environmental fields. The inherent physical separation between the discharge layer and the downstream target causes a reduction in the flux of reactive chemical species, resulting in the limitation of application efficacy. To obtain the development of healthcare devices, this contribution focuses on the spatial-temporal transport behavior of OH radicals generated by SMD devices in helium using laser induced fluorescence and optical emission spectroscopy with hexagon mesh electrode of lattice distance varying between 3 mm and 11 mm. It was observed that the lattice distance has a significant impact on the distribution of OH radicals and the uniformity of the SMD. The increased lattice distance of the hexagon mesh both increased the density, delivery distance and propagation velocity of OH radicals. When the lattice distance varied from 3 to 11 mm, the generated OH was spread over twice the distance. The maximum delivery distance was found to be approximately 10.4 mm under lattice distance of 11 mm condition, and the peak propagation velocity was estimated to be about 3.8 mm ms(-1). For the main distribution region of OH, the optimum lattice distance is 9 mm. In addition, the distribution region rapidly expands between 7 and 9 mm. However, the findings indicated that researchers should make a compromise between the delivery of reactive chemical species and uniformity. The decreased lattice distance facilitated a high degree of uniformity for reactive species on a downstream target, which is a key requirement in healthcare related areas.