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Diffuse Coplanar Surface Barrier Discharge in Artificial Air: Statistical Behaviour of Microdischarges

100%

Čech J., Hanusová J., Sťahel P., Černák M.

Open Chemistry

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2015

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vol. 13

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issue 1

EN

Diffuse Coplanar Surface Barrier Discharge (DCSBD) is a novel type of atmospheric-pressure plasma source developed for high-speed large-area surface plasma treatments. The statistical behavior of microdischarges of DCSBD generated in artificial air atmosphere was studied using time-correlated optical and electrical measurements. Changes in behavior of microdischarges are shown for various electrode gap widths and input voltage amplitudes. They are discussed in the light of correlation of the number of microdischarges and the number of unique microdischarges’ paths per discharge event. The ‘memory effect’ was observed in the behavior of microdischarges and it manifests itself in a significant number of microdischarges reusing the path of microdischarges from previous half-period. Surprisingly this phenomenon was observed even for microdischarges of the same half-period of the discharge, where mechanisms other than charge deposition have to be involved. The phenomenon of discharge paths reuse is most pronounced for wide electrode

2

Nonthermal plasma modification of polypropylene fibres for cementitious composites

76%

Morávek T., Fialová M., Kopkáně D., Ráheľ J., Sťahel P., Černák M.

Open Chemistry

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2015

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vol. 13

|

issue 1

EN

The plasma treatment of polypropylene fibres used as concrete admixtures for improving its mechanical properties is the focus of this research paper. A plasma treatment was conducted in a low-temperature plasma environment at atmospheric pressure in a DCSBD (Diffuse Coplanar Surface Barrier Discharge). The degree of hydrophilicity caused by the plasma treatment was determined by measuring the rate of penetration of water into the porous media, commonly referred to as the Washburn method. The influence of the addition of PP (polypropylene) fibres to the concrete matrix was investigated using a three point bending test which determined the flexural strength of concrete samples. Our experiments demostrate that plasma improves both the wettability of PP fibres and its adhesion to the concrete matrix. The tests of flexural strength show, that even a short plasma treatment (5 s) can have a significant impact on the mechanical properties of fibre-reinforced concrete composite.

3

Properties of atmospheric pressure plasma oxidized layers on silicon wafers

76%

Skácelová D., Sládek P., Sťahel P., Pawera L., Haničinec M., Meichsner J., Černák M.

Open Chemistry

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2015

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vol. 13

|

issue 1

EN

In this research a new process of plasma oxidation of crystalline silicon at room temperature is studied. The plasma oxidation was carried out using Diffuse Coplanar Surface Barrier Discharge (DCSBD) operating in ambient air and oxygen at atmospheric pressure. The influence of exposition time, plasma parameters and crystallographic orientation of silicon on oxidized layers and their dielectric properties were investigated. Thickness, structure and morphology of these layers were studied by ellipsometry, infrared absorption spectroscopy and scanning electron microscopy. During the treatment time, from 1 to 30 minutes, oxidized layers were obtained with thickness from 1 to 10 nm. Their roughness depends on the crystallographic orientation of silicon surface and exposure time. Electrical parameters of the prepared layers indicate the presence of an intermediate layer between silicon substrate and the oxidized layer.

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3 Open Chemistry

3 2014

3 Sťahel P.

3 Černák M.

1 Fialová M.

1 Haničinec M.

1 Hanusová J.

1 Kopkáně D.

1 Meichsner J.

1 Morávek T.

1 Pawera L.

1 Ráheľ J.

1 Skácelová D.

1 Sládek P.

1 Čech J.

Diffuse Coplanar Surface Barrier Discharge in Artificial Air: Statistical Behaviour of Microdischarges

Nonthermal plasma modification of polypropylene fibres for cementitious composites

Properties of atmospheric pressure plasma oxidized layers on silicon wafers