XJTU: Typical Arrangements for Downstream Uniformity Assessment in Atmospheric-Pressure Plasma Jet Arrays

The downstream uniformity of the atmospheric-pressure plasma jet array is a key technical problem in regards to large-scale applications. This paper presents a 2-D array device of five jets arranged in four different shapes designed from the perspective of symmetry. Various schemes were tested to determine the effects of jet arrangement on the downstream uniformity of the array: the completely symmetrical array X, the completely asymmetrical array J, and semi-symmetrical arrays T and U. The interactions in the arrays were observed via optical imaging as well as electrical and spectroscopic characterizations. The results show that the downstream plume pattern markedly changes with the jet arrangement. Peripheral plumes suppress the internal plumes to varying extent under different jet arrangements. The emission intensity of the helium line at 706.5 nm was taken as a criterion to find that downstream uniformity under the arrangements J, T, U, and X gradually decreases as the jet arrangement grows increasingly symmetrical. The electric field simulation shows that different jet arrangements cause various degrees of inhomogeneous electric field distributions, which in turn affect the charge transferred into each plasma jet and the distributions of active particles resulting in downstream uniformity variations. The results presented here may provide a theoretical foundation for improving the downstream uniformity of the plasma jet arrays and achieving large-scale plasma jet sources.