This paper discusses the possibility of producing high concentrations of O2(a1Δg) states at pressures up to atmospheric in
rare-gas/oxygen/NO mixtures by using micro-plasmas. Micro-plasmas refer to electric discharges created in very small
geometries which have been proven able to operate in DC mode at high pressure and high power loading without
undergoing any glow to arc transition. The so-called Micro Cathode Sustained Discharge (MCSD), which is a three-electrode
configuration using a Micro Hollow Cathode Discharge (MHCD) as a plasma cathode, can be operated as a
non-self-sustained discharge with low values of the reduced electric field and of the gas temperature. As a result, these
MCSDs can efficiently generate large amounts of singlet delta oxygen. In Ar/O2/NO mixtures, at an oxygen partial
pressure of 10 mbar, high values of O2(a1Δg) number density (1.5 1016 cm-3) and of the production yield (6.7 %) can be
simultaneously obtained. For lower O2 partial pressure, yields higher than 10 % have been measured. In He/O2/NO
mixtures, O2(a1Δg) number densities around 1016 cm-3 were achieved at atmospheric pressure for flow rates in the range
5-30 ln/mn, which could give rise to new applications.
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