Influence of frequency on O2(a 1Δ) and oxygen atom production in transverse radio-frequency discharges

Experimental investigations of radio-frequency discharges in O2/He/NO mixtures in the pressure range 1-100 Torr and power range 0.1-1.2 kW have indicated that O2(a 1Delta) production is a strong function of geometry, excitation frequency, pressure and diluent ratio. The goal of these investigations was maximization of both the yield and the flow rate (power flux) of O2(a 1Delta) in order to produce favourable conditions for application to an electric oxygen-iodine laser (EOIL). At lower pressures, improvements in yield are observed when excitation frequency is increased from 13.56 MHz. As pressure is increased in the baseline 50 mm gap configuration, increasing excitation frequency becomes detrimental. O2(a 1Delta) yield performance is improved at high pressure by reducing the discharge gap and increasing the diluent ratio. Numerous measurements of O2(a 1Delta), oxygen atoms and discharge excited states are made in order to describe the discharge performance dependent on various parameters.