We report a study of electron saturation current variations at varying probe heating that were found to be closely related to probe wire contamination. The study was performed in three types of low temperature argon plasma -the weakly magnetized plasma of a cylindrical magnetron, the non-magnetized plasma of a double plasma machine and a hollow cathode plasma jet, showing different trends. In the present work the effect of overestimation of the plasma potential by a strongly emitting probe is discussed and experimental data are compared with a theoretical model.

We report on experimental investigations of the change of the electron saturation current of a dc-heated emissive probe with the probe heating current. According to the simple theory of the emissive probe, the electron saturation current should not be affected by emission. However, in many experiments a variation of the electron saturation current with the emission current was observed. We consider two possible reasons for such variations: (a) the influence of the space charge around the probe shaft, (b) the change of the work function of the probe surface material due to heating. We tried to find sufficient experimental evidence for supporting one or the other (or both) of these two explanations. We used two different types of plasma to validate the results: a cylindrical magnetron plasma and the non-magnetized plasma of a DP machine. From our experiments follows that the electron saturation current of the emissive probe is affected by the space charge effect as well as it depends on the probe wire material. : 52.25.Xz, 52.70.Ds PACS

This contribution describes the results of the measurements that were made with emissive probe in the argon dc discharge in the cylindrical magnetron. Main part of this emissive probe -the tungsten wire loop -was heated by the dc current to raise its temperature up to that allowing to reach the requested emission current. With such a probe we measured the dependence of floating potential on the heating current or voltage, I-V characteristics of the probe and radial distribution of potential between anode and cathode. Main goal of the measurements was the evaluation of plasma potential inside the magnetron and finding evidence, whether these methods bring us advantage for plasma potential estimation with respect to commonly used Langmuir probe method. For that purpose we compared several ways used for obtaining the plasma potential: (i) from the inflection point of the cold probe characteristic (ii) from the floating potential of sufficiently heated emissive probe (iii) from the abscissa of the crossing point of the cold and emissive probe characteristic (iv) from the ionization potential of the discharge gas (argon). : 52.25.-m PACS

DC energized hollow cathode plasma jet system was examined by radially movable Langmuir probe. Radial distribution of electron concentration, plasma and floating potentials and mean electron energy were obtained from measured probe characteristics at the distance 17 mm downstream of the hollow cathode -nozzle. The radial dependence of plasma parameters was measured for distances from the system axis 0-120 mm in the discharge containing Ar and O2. Two scenarios were used: addition of O2 into the nozzle and into the plasma vessel. The differences in measured floating and plasma potential, electron density and mean electron energy radial courses obtained in the two scenarios are qualitatively explained. In addition temporal dependences of main plasma parameters for discharges in clean argon and argon-oxygen mixture were investigated that demonstrate system stability and its applicability for deposition of layers containing Ti. TiOx thin films were deposited onto glass substrates and examined by AFM and ellipsometry. It is illustrated that the differences in plasma parameters in the two scenarios of oxygen addition influence the layer properties.

A cw/pulsed radiofrequency discharge coupled by electrodes in coaxial arrangement was used to dissociate iodine atoms from CH 3 I or CF 3 I molecules diluted in a carrier gas (a mixture of Ar and He). The discharge chamber was arranged directly inside an iodine injector (made of aluminum) to minimize the recombination of generated atomic iodine and enabling an increased assistance of UV light for a photo-dissociation enhancement of I atoms production. The effluent of the discharge chamber/iodine injector was injected into the flow of N 2 downstream the nozzle throat. Measurements of I atoms concentration distribution at different distances from the injection and in two directions across cavity were done by means of absorption measurements at the wavelength of 1315 nm. Dependences of atomic iodine concentration on main RF discharge parameters and flow mixing conditions were measured. This novel method could be an alternative to the chemical generation of atomic iodine and also an efficient alternative to other electric discharge methods of I atoms generation for chemical oxygen-iodine laser (COIL) and discharge oxygen-iodine laser (DOIL).