Jan Čech

Deposition of thin organosilicon polymer films in atmospheric pressure glow discharge

The atmospheric pressure glow discharge burning in nitrogen with small admixture of organosilicon compounds such as hexamethyldisilazane or hexamethyldisiloxane was used for the deposition of thin organosilicon polymer films. The properties of the discharge were studied by means of optical emission spectroscopy and electrical measurements. The deposited films were characterized by atomic force microscopy, x-ray photoelectron spectroscopy, infrared transmission measurements, ellipsometry, depth sensing indentation technique and contact angle measurements. The films were polymer-like, transparent in the visible range, with uniform thickness and without pinholes. The film hardness varied from 0.3 to 0.6 GPa depending on deposition conditions, the elastic modulus was in the range 15-28 GPa and the surface free energy was in the range 26-45 mJ m-2. The studied films exhibited good adhesion to the substrate.

Permanent hydrophilization of outer and inner surfaces of polytetrafluoroethylene tubes using ambient air plasma generated by surface dielectric barrier discharges

We present an atmospheric pressure ambient air plasma technique developed for technically simple treatment of inner and/or outer surfaces of plastic tubes and other hollow dielectric bodies. It is based on surface dielectric barrier discharge generating visually diffuse plasma layers along the treated dielectric surfaces using water-solution electrodes. The observed visual uniformity and measured plasma rotational and vibrational temperatures of 333 K and 2350 K indicate that the discharge can be readily applied to material surface treatment without significant thermal effect. This is exemplified by the obtained permanent surface hydrophilization of polytetrafluoroethylene tubes related to the replacement of a high fraction (more than 80%) of the surface fluorine determined by X-ray photoelectron spectroscopy. A tentative explanation of the discharge mechanism based on high-speed camera observations and the discharge current and voltage of measurements is outlined.

ENERGY EFFICIENCY OF PLANAR DISCHARGE FOR INDUSTRIAL APPLICATIONS

Diffuse Coplanar Surface Barrier Discharge has proven its capabilities as an industry-ready plasma source for fast, in-line and efficient plasma treatment at atmospheric pressure. One parameter required by industry is energy efficiency of the device. In this paper, we present the energy efficiency of the whole plasma system, and we investigate possible sources of errors.

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

Abstract 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 Graphical Abstract

INFLUENCE OF SUBSTRATE THICKNESS ON DIFFUSE COPLANAR SURFACE BARRIER DISCHARGE PROPERTIES

In presented work the influence of dielectric barrier thickness on the parameters of Diffuse Coplanar Surface Barrier Discharge was investigated. The discharge was operated at atmospheric pressure laboratory air. The electrical parameters of the system were studied both experimentally and using numerical simulations. The discharge pattern was studied as well using intensified CCD camera.

DIFFUSE COPLANAR SURFACE BARRIER DISCHARGE IN NITROGEN:MICRODISCHARGES STATISTICAL BEHAVIOR

We studied statistical behavior of microdischarges of diffuse coplanar surface barrier discharge (DCSBD) operated in nitrogen atmosphere at two input voltage regimes. We measured spectrally unresolved discharge patterns together with discharge electrical parameters using high-speed iCCD camera and digital storage oscilloscope. External synchronization enabled us to measure the discharge pattern during positive and/or negative half-period of input high voltage in the single-shot mode of operation. The comparison of microdischarges behavior during positive, negative and both half periods of input high voltage was performed for two levels of input voltage, i.e. voltage slightly above ignition voltage and high above ignition voltage (“overvoltage”). The number of microchannels crossing discharge gap was counted and compared with number of microdischarge current peaks observed during corresponding half-period of input high voltage. The relations of those incidences was shown and discussed.

Thermal stability of coatings prepared in atmospheric pressure glow discharge

In order to better understand the relations between the deposition conditions, the microstructure and hydrogen and/or nitrogen incorporation in polymeric films the thermal stability of coatings prepared in atmospheric pressure glow discharge was studied. The polymeric films were prepared from the mixture of hexamethyldisiloxane (HMDSO) or hexamethyldisilazane (HMDSZ) with nitrogen in atmospheric pressure glow discharge (APGD). The hydrogen and/or nitrogen evolved from polymeric films were studied by ther.