Ing. Jan Sláma

The present proposal was developed in the frame of the project Strengthening capacities of the National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” in the field of quality and inclusion in education, internationalization and support of cooperation supported by the project of the Ministry of Foreign Affairs of the Czech Republic “Strengthening the capacity of public universities in developing countries”. It is focused on the development of a conceptual strategy and the transfer of Czech know-how in the field of quality and inclusion of the educational process, its management and internationalization.

A problematics of low temperature plasma diagnostic will be briefly foreshadowed. As the atmospheric discharges often transit into channel regime, monitoring of the discharge channels is required. Therefore three ways of stydy will be presented. Integral image taking by standard photo camera, instant images taken by high-speed camera and a method of multi-segmented electrode will be given as a possible way how to detect discharge channel distribution. The idea of multi-segmented electrode will be shown on two basic set-ups: tip to plane and tip to sphere electrode configuration. A concept and simulation of a low-cost signal converter will be presented as an ideology concept for further investigation and physical realization.

Discharges generating low temperature plasma at atmospheric pressure have the potential to treat surfaces biologically contaminated by organic matter in a non-destructive manner. We have been studying ways of inhibiting the growth of microorganisms with the use of dielectric barrier discharge (DBD) plasma. The effect of the choice of a barrier material and its thickness on the germicide properties of the DBD is described. We used Saboraud agar inoculated by 105 cfu/cm2 of Candida albicans yeast as the model contaminated surface. After cultivation, the proportion of the treated surface with no C. albicans colony was evaluated.

Two types of dielectric barrier discharge (DBD) powering principles were compared in this study. The variable autotransformer (sinusoidal shaped voltage) and the semiconductor H-bridge converter generating pulse width modulation (PWM, square wave shaped voltage) were used as a voltage source. Differences were found in the discharge current waveforms. Powering the DBD by PWM provides promising features for plasma application.

Filamentary and quasi-homogeneous mode of dielectric barrier discharge (DBD) was investigated as a plasma source with fungicidal effect on Candida albicans yeast inoculated on Sabouraud agar wafers. As compared with the filamentary DBD mode, the quasi-homogeneous mode had significantly better results: shorter exposition time needed for inhibiting C. albicans yeast, moreover the quasi-homogeneous mode had gentle influence on the agar surface structure.

Advanced oxidation processes were originally developed for low-temperature water cleaning processes. They are based on production of high oxidative radicals like atomic oxygen or OH groups, which destroy various organic pollutants. Atmospheric plasma discharges belong to high-effective sources of oxidizing radicals. Among various methods of plasma production at atmospheric pressure, the gliding arc belongs to sources with high industrial potential because of its high efficiency and simple construction. For proper and quick employment and particular process optimization detailed knowledge of plasma source parameters is of great importance. We will present results of complex investigation of an gliding arc discharge and optimization of an gliding arc head construction for industrial applications. Using proper diagnostic techniques optimal working conditions were set for different applications. Examples of particular applications of the gliding arc will be given.

Germination and early growth of buckwheat (Fagopyrum aesculentum) after low-temperature plasma discharge treatment in air gas generated in various devices were tested. Three pre-treatment times were used: 180 s, 300 s and 600 s. Seed cultivation was carried out in laboratory conditions. Number of germinating seeds was counted, length and weight of seedling sprouts were measured. The data were analysed with two-way ANOVA: a significant influence of the type of plasma apparatus, time of exposure and combination of both factors were found. A positive effect on germination and early growth was observed after the application of GlidArc device (low-temperature plasma generated in air gas under atmospheric pressure between two electrodes). The opposite effect of surface dielectric barrier discharge (SDBD) apparatus, which is characterized by plasma with high power density, was observed. Shorter pre-treatment times for SDBD device must be therefore used. Effects of seed germination and early growth of seeds strongly depended on the type of the used plasma apparatus.

This paper deals with the plasma flow shape depending on the electrode form of a gliding discharge plasma-chemical reactor, and with the temperature distribution along the direction of the plasma flow in one specific electrode form. The shape of the electrodes and their mutual position has a significant influence on the design of a gliding discharge reactor and its applications. It is crucial to know the temperature distribution in the reactor's chamber design and discharge application. Three configurations with model shapes of wire electrodes were therefore tested (low-divergent, circular, high- divergent) and the plasma flow was described. The experiments were performed in air at atmospheric pressure and at room temperature. In order to map the reactive plasma region of the flow we investigated the visible spectral lines that were emitted. The gas temperature was measured using an infrared camera.

Contribution deals with form of electrodes and corresponding shape of plasma flow in the gliding discharge reactor. Gliding discharge sustained in air at atmospheric pressure and room temperature. There were studied three elemental electrodes configuration. Plasma was investigated by means of its visible spectral lines for identification of the most reactive plasma region in the flow. Results can be helpful in shaping of the gliding discharge reactor ionized gas region.

The plasma flow temperature distribution at atmospheric pressure was investigated by test probes made from solid matter. Temperature of solid matter probes was measured by thermo camera for working gas flow rates 10, 20 and 30 slm. Temperatures up to 200 °C were detected. The results are usable for application of plasma surface treatment.

Paper deals with plasmaflow shape depending on electrode form of gliding discharge plasma-chemical rector and axial temperature distribution in one type of the reactor. The experiments were performed in air of atmospheric pressure and room temperature. For mapping the flow's reactive plasma region we investigate emitted visible spectral lines. Gas temperature was measured by thermo camera. Proper shape of electrodes and their mutual position has significant influence on design of gliding discharge reactor and it's applications therefore three elementary configurations of wire electrodes were tested (low-divergent, circular, high-divergent) and plasma flow was described. Knowledge of temperature distribution is crucial in reactor's chamber design and discharge application.

We investigated connection between form of electrodes and shape of the plasma ow. Experiments were performed in air at atmospheric pressure. For identification of the most reactive plasma region in the ow, plasma was investigated by means of its visible spectral lines. There were tested three basic configurations of wire electrodes representing their limit forms (low-divergent, circular, high-divergent) and recognized ionized regions of the ow. Results can be used in decision making about shaping of the gliding discharge reactor ionized gas region, especially in case when both volume and surface treatment is needed.

Radicals and ions generated in discharge sustaining in proper gas together with its intense ultraviolet radiation are suitable to break molecular bonds and initiate physical and chemical processes in uppermost atomic layers of a material surface. Polyester is one of the most produced and used textile component, unfortunately it is also known with some unwanted properties, e.g. high hydrophobicity, electrostatic charge creation, pilling etc. To influence the efficiency of this process, we tried to increase the input energy of the plasma reactor by means of the supply voltage frequency. Correlation of the supply voltage frequency and modification efficiency presented by hydrophilicity changes expressed by means of the area of feathering time evolution (drop test) is described in this paper. Experiments proved that growing reactor input energy/supply voltage frequency shortened necessary modification time.

Study the possibility of atmospheric dielectric barrier discharge (ADBD) application for TiO2 thin film deposition. Thin films were deposited on polymeric substrates with PECVD method with titanium tetraisopropoxide (TTIP) as a precursor. Exploration was mostly focused on the influence of Ar/TTIP and oxygen gas flow rates on the plasma deposition process. and surface properties of the thin TiO2 films on polystyrene substrates

This paper considers design and construction of middle frequency high voltage transformer. Application of this transformer is for supplying atmospheric dielectric barrier discharge at Faculty of Electrical Engineering Czech Technical University in Prague. The requirements for this transformer are: 20 kV AC sine output, frequency range from 2 up to 20 kHz and up to 5 mA output current. In the conclusion we can find out the modifications of the transformer.

Final characteristics of polymers are the compromise between wanted surface and bulk properties. Important change of the polymer use-value can be caused by modification of characteristics of its upper structural units (i.e. in region under the surface deep some tens of nanometers). These changes - and modification - can be performed i. a. by treatment with the "cold" plasma and moreover with low costs and minimum environmental impact. Modification of polymer surface characteristics may proceed during functionalization, when plasma particles react with polymer surface molecules and new chemical functional groups are formed on polymer surface. These chemical reactions can be influenced with composition of atmosphere in the plasma reactor, e.g. application of oxygen plasma leads to polymer surface energy and wettability increase. To evaluate the efficiency of this process, we studied connection of the ADBD supply energy/voltage frequency and changes of the polymer