Generation of Energetic Species by RF Microplasma Arrays

We present preliminary results from the first implementation of a prototype single-board RF micro-discharge, linear array device in a discharge-flow reactor for quantitative determinations of ozone and singlet-oxygen production from microplasmas in O$_{2}$ and air at 1 atm. The ultimate objective is to develop compact, portable low-power micro-discharge based systems to generate energetic species for atmospheric-pressure applications including decontamination and disinfection. The technology uses application of low DC voltages and low applied powers ($\sim $25 W) at $\sim $1 GHz frequencies, across small gaps in arrays of resonators to ignite and sustain highly energetic microplasmas at elevated pressures. A set of 15-resonator micro-discharge assemblies was designed, fabricated, and tested in static and flowing environments for O$_{2}$, air, and Ar flows at pressures of 20 Torr to 1 atm. O$_{3}$ production was measured by UV absorption spectrometry, and O$_{2}$(a$^{1}$delta-$_{g})$ (``singlet-oxygen'') concentrations were determined by absolute near-infrared emission spectroscopy. Near-infrared emission spectra from an argon plasma were also recorded, and showed extensive excitation of the Ar(I) 3p$^{5}$4p -- 3p$^{5}$4s emission system near 12 eV.