ИСТИНА

In this study, the 80 MHz symmetric CCP discharge in quartz tube was used as a source of pure O2 plasma of increased pressures (10 to 100 Torr). This research is mainly focused on the balance of O atoms that is governed by processes of O2 dissociation and O atom loss. The use of time-resolved actinometry technique in the modulated discharge allowed experimentally determining dissociation rate constant kO2-diss and atom loss frequency γO loss. The O atom loss is connected with surface recombination at lower pressure and volume reactions at higher pressure. The variation of plasma parameters allowed varying gas temperature from 500 K up to 1800 K and this allowed to study the O atom generation and loss mechanisms in a wide range of gas conditions. The behavior of kO2-diss at low E/N and the role of ozone in γO loss is discussed in detail. This research is supported by Russian Foundation for Basic Research (RFBR) Grant No. 16-52-16024.