ИСТИНА

Electric discharges in molecular oxygen are widespread in nature and in technological applications including surface processing and plasma-medicine. Although they have been studied for a very long time, much fundamental data is still lacking; for example there is no consensus on electron-impact dissociation cross-sections near threshold, and no reliable predictive model for surface catalysed atom recombination. In this study we combine a range of novel state of the art diagnostic techniques to determine the absolute densities and loss kinetics of all major neutral species (atoms, ground and metastable atoms), in order to test and improve O2 plasma cross-section and reation rate sets as well as probing surface reaction mechanisms. We have chosen to study DC positive column discharges in pure O2 in a pyrex tube, because this allows the generation of a stable, reproducible homogeneous plasma over 10’s of cm with constant reduced electric field (without the strong temperature and gas density gradients present in processing-type low-pressure plasmas), ideal for rigorous comparison with models.