Study of a 2.45 GHz microwave micro-plasma in air

This paper studies a 2.45 GHz microwave micro-plasma source, working in air at atmospheric pressure. The discharge, similar to the one developed by Kono \textit{et al }[1], is sustained within a slit (50-200 $\mu$m wide and 1.4cm width) delimited by two metallic blades placed at one end of a microstrip line. At the other end, a movable short circuit works as an impedance matching unit. The plasma source is placed inside a microwave absorbent box. The power coupling is analyzed theoretically by using the commercial software CST Microwave Studio{\textregistered}, and experimentally by taking the ratio of the reflected to incident power, with and without plasma and for different slit sizes. A spatially resolved optical emission spectroscopy study was also realized, using the SPECAIR{\textregistered} software [2] to deduce the gas temperature $T_{g}$ along the plasma width. In general, $T_{g}$ is found between 650 and 1650 K, for 60-140W input power and 50-200 $\mu$m slit size. \newline [1] A. Kono, T. Sugiyama, T. Goto, H. Furuhashi, Y. Uchida, \textit{Jpn. J. Appl. Phys. }Vol. 40 (2001) pp. L238-L241 \newline [2] http://www.specair-radiation.net/