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Processes of Nanoparticle Formation in Low Temperature Plasma
Brožek, V. ; Mastný, L. ; Moravec, Pavel ; Neufuss, Karel ; Ondráček, Jakub ; Ždímal, Vladimír
This work describes the synthesis of nanoparticles during interaction of several different metals (Ag) or their respective oxides (TiO2, Cr2O3) with oxygen-hydrogen plasma having temperatures above 25000 K. Resulting nanoparticles and/or their aggregates in the size range of 25-300 nm were deposited on metallic targets and/or trapped in the water filters and separated using ultra-centrifugal apparatus. The aerosol spectrometer SMPS 3936 (scanning mobility particle sizer) was used to study the particle size distribution of generated nanoparticles in the size range 14 – 700 nm. In order to extend the measured particle size range towards larger sizes, the APS 3321 spectrometer (aerodynamic particle sizer) with the size range 500-20000 nm was used simultaneously. Both spectrometers were set-up to sample with three minute time resolution. Process conditions and production of inorganic nanoparticles of defined composition are discussed in this work.
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Residual aberrations of Clark 8“ telescope of Ondřejov
Rail, Zdeněk ; Jareš, Daniel ; Lédl, Vít
This paper deals with residual aberrations of Clark 8“ (diameter 203 mm) lens of Astronomical Institute of AS CR,v.v.i. in Ondřejov. Objective was disassembled and cleaned in Development Optical Workshop of AS CR in Turnov in 1999. During this process optical parameters of lenses were measured and this makes possible to evaluate mathematical simulation of this dublet.
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Catadioptric systems of Argunov, Popov and Klevcov
Rail, Zdeněk ; Jareš, Daniel ; Lédl, Vít
This paper deals with two-mirror systems of Argunov, Popov and Klevcov which use meniscus correctors in convergent beam of light placed near their secondaries. These systems make possible to construct of highly aberration corrected devices. Several telescopes of this type are producted commercialy and belong to the best corrected catadioptric systems.
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Chemical aspects of the anti-ballistic armors preparation by plasma deposition
Brožek, V. ; Chráska, T. ; Mušálek, R. ; Neufuss, Karel
This paper informs about possibility to deposit ceramic-metallic composites on different types of metallic and ceramic substrates by thermal spraying, namely plasma spraying. Preparation of free-standing deposits as well as metal-reinforced composites is described. Results of plasma deposition of two ultra-hard ceramic materials (titanium boride and nitride) are presented in more details. Plasma deposition of materials carried out in specific technological conditions preventing undesirable high-temperature oxidation of ultra-hard ceramics is costly. Therefore, deposition conditions which should lead to improvement of surface properties of currently used antiballistic ceramics were studied and described.
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Aerosol Nanoparticles Formed during Plasma Deposition
Ždímal, Vladimír ; Moravec, Pavel ; Doležal, B. ; Brožek, Vlastimil ; Neufuss, Karel
Results of pilot-plant experiments on a plasmatron WSPR constructed at the Institute of IPP AS CR are shown in this paper, dealing with plasma deposition of the ultrafine and fine aerosol fractions of some metallic materials. In this work we concentrated on its side-product investigating the ultrafine particles released during the process into the aerosol phase. The aerosol particle size distribution was studied in a near real time using the state-of-the-art aerosol spectrometers operated by the ICPF AS CR. It was verified that these instruments are able to take aerosol samples in the close vicinity of a high-temperature plasma and still provide sensible results. In the present work we discussed the possibility to produce aerosol nanoparticles of a defined composition and properties by the plasmatron technique.
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Status of Magnetic Diagnostics on COMPASS
Havlíček, J. ; Kudláček, O. ; Janky, F. ; Horáček, Jan ; Beňo, R. ; Valcárcel, D.F. ; Fixa, J. ; Brotánková, Jana ; Zajac, Jaromír ; Hron, Martin ; Pánek, Radomír ; Cahyna, Pavel
The COMPASS tokamak is in a test operation after its reinstallation in Institute of Plasma Physics AS CR in Prague (IPP Prague) in the year 2008. This operation consists of commissioning of various diagnostics and tokamak auxiliary systems. This paper presents current status of magnetic diagnostics after its refurbishment, used method of the calibration and shows examples of magnetic diagnostics utilization for plasma position reconstruction as well as for vertical hydraulic preload interlock system.
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Experimental investigation of electric arc behavior during cutting of stainless steel
Kavka, Tetyana ; Mašláni, Alan ; Konrád, Miloš ; Tossens, S.
The present work is devoted to experimental investigation of electric arc behaviour during cutting of stainless steel. The goal of this work is to define influence of arc voltage fluctuations and anode attachment behaviour on the cutting performance. In most cases the anode attachment was verz luminous and was observed far from the main arc column close to the plate top. The cut material exhibited stronger surface roughness at the anode attachment location. The measured voltage traces showed a so-called restrike mode of oscillations of different frequencies and amplitudes.
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Role of UV radiation, solution conductivity and pulse repetition frequency in the bactericidal effects during pulse corona discharge in water
Špetlíková, E. ; Janda, V. ; Lukeš, Petr ; Člupek, Martin
Inactivation of bacteria Escherichia coli and Enterococcus faecalis by the pulsed corona discharge in liquid phase has been investigated. The reactor with point to plate geometry of electrodes was used for generation of the discharge in liquid phase. The effects of the solution conductivity and the pulse repetition frequency on the bacterial inactivation have been determined. Better efficiency of inactivation was observed for both types of bacteria with the increasing solution conductivity and the pulse repetition frequency since E. faecalis was more sensitive to these changes then E. coli. The role of UV radiation emitted by the electrical discharge in the overall bacterial efficiency was evaluated in dependence on the solution conductivity using UV light transparent spectrometric cell. It was determined that UV radiation contributes about 40% to the overall inactivation of bacteria by the discharge.
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