Volume processing of gas using two-dimensional microplasma arrays

Summary form only given. Non-thermal microplasma sustained at atmospheric pressure is a very promising technology for thin film deposition, biomedical engineering, and chemical sensors. However, microplasma with small size is ineffective in the treatment of large scale substrates or large gas flows. Arrays of microwave resonators, however, have opened the possibility of generating stable, moderate volume atmospheric plasma as shown in our previous studies. In this work, a two-dimensional microplasma array geometry is realized by stacking two microwave substrates face to face. Each of these boards hosts an array of seven quarter-wavelength microstrip resonators. A single microwave power input was attached to the middle resonator of the array powers both boards at their resonant frequency (0.85 GHz) without any electrical connections. Plasma is generated at the open-end of each of the 14 resonators and partially fills the volume between the two adjacent resonator arrays. Coupled-mode theory is used to interpret the electromagnetic interactions between the dual resonator arrays. Operation of the dual arrays is demonstrated in both argon and argon/oxygen mixtures. Optical emission from the rotational structure of the A ²Δ -X ²Π transition of the contaminant CH radical is observed near 431 nm and fit to extract the gas temperature within the discharge. Spatially resolved measurements of gas temperature, important for modeling reaction rates in such plasmas, are presented as functions of gas flow rate and input power.