Martina Mrázková

On the oxygen addition into nitrogen post-discharges

It is well known that the dissociation degree of nitrogen can be substantially increased if a small amount of oxygen is added into an active discharge. In this work it is experimentally shown that a very similar phenomenon occurs also when oxygen is added into the nitrogen late post-discharge. A detailed kinetic model, valid for the oxygen addition into the active discharge, fails to interpret these new experimental observations, and, consequently, its completeness has to be questioned.

Simultaneous measurement of N and O densities in plasma afterglow by means of NO titration

In this work we describe a method based on NO titration that permits us to measure at the same time the absolute concentrations of N and O atoms in the gas phase. This method is suitable for low concentrations of oxygen atoms. We also discuss the validity of the titration method, especially the influence of the reaction time. It was used to study the influence of O2 admixture on the degree of dissociation of nitrogen in the afterglow. The results of the NO titration technique were compared with those obtained by means of electron paramagnetic resonance and with the relative values determined from emission of .

Plasma diagnostics using electron paramagnetic resonance

Methods giving absolute concentrations of various species in the plasma are of utmost importance to plasma research. Besides currently prevalent laser methods, a method based on microwave absorption—electron paramagnetic resonance—can be successfully used for plasma diagnostics. It is able to detect many atoms, molecules and radicals in the ground or excited states. In this paper we give an overview of the method and several practical examples. (Some figures in this article are in colour only in the electronic version)

EPR measurements in hydrogen post-discharge

We measured the atomic hydrogen concentration in the afterglow in a quartz tube by means of EPR. A small amount of nitrogen was added into the afterglow. In order to study the processes in the afterglow the nitrogen injector was placed in distance from the discharge high enough to avoid the nitrogen penetration into the discharge. A strong increase of the atomic hydrogen concentration in the gas and a decrease of the hydrogen recombination on the quartz walls was observed.