DC glow discharge sustained in oxygen is employed in various technological applications such as thin layer deposition. Assuming pressures of hundreds of pascals, two different forms of positive column of the discharge co-exist: high-gradient H-form and low-gradient T-form.
The existence of both forms mostly depends on pressure and discharge current, but it is also influenced by purity of the gas used, e. g., small addition of nitrogen can have great influence. Our experiments focus on spectroscopic study of the two forms of discharge and on the transition region between these two forms.