Number of found documents: 507
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Zbytkové vady Gajduškova objektivu o průměru 200 mm a ohniskové vzdálenosti 3480 mm Hvězdárny a planetária v Hradci Králové
Rail, Zdeněk; Melich, Zbyněk; Šrajer, Bohdan; Vápenka, David; Tomka, David; Thoř, Tomáš; Macner, David
2020 - Czech
Achromatický dublet o průměru 200 mm a ohniskové vzdálenosti 3480 mm byl vyroben profesorem ing. Vilémem Gajduškem v Ostravě v roce 1954. Dalekohled s tímto objektivem je umístěn na Hvězdárně a planetáriu v Hradci Králové. Objektiv byl v roce 2018 restaurován v Ústavu fyziky plazmatu, v.v.i.-Centru Toptec v Turnově. Čočky byly přeměřeny a z naměřených hodnot jsme vyčíslili jeho zbytkové optické vady. Výsledky simulace přinášíme v této práci. The achromatic dublet of diameter 200 mm and focal length 3480 mm was manufactured by Professor ing. Vilém Gajdušek in Ostrava in 1954. The telescope with this objective is placed at the Observatory and planetarium in Hradec Králové. The objective was restored in the Institute of Plasma Physics, v.v.i.-Centrum Toptec in Turnov. During the process lens was measured and data were used for evaluation of its residual aberrations. We present the results of the measurement in this paper. Keywords: achromatic dublet; aplanat; coma; pherochromatic aberration Available at various institutes of the ASCR
Zbytkové vady Gajduškova objektivu o průměru 200 mm a ohniskové vzdálenosti 3480 mm Hvězdárny a planetária v Hradci Králové

Achromatický dublet o průměru 200 mm a ohniskové vzdálenosti 3480 mm byl vyroben profesorem ing. Vilémem Gajduškem v Ostravě v roce 1954. Dalekohled s tímto objektivem je umístěn na Hvězdárně a ...

Rail, Zdeněk; Melich, Zbyněk; Šrajer, Bohdan; Vápenka, David; Tomka, David; Thoř, Tomáš; Macner, David
Ústav fyziky plazmatu, 2020

Digitalizace Maksutovovy komory 350/840 úpické observatoře
Rail, Zdeněk; Melich, Zbyněk
2019 - Czech
Maksutovova komora o průměru 350 mm a ohniskové vzdálenosti 840 mm byla vyrobena v Turnově počátkem 80. let. Na úpické observatoři sloužila k fotografování oblohy na fotografický film. V současné době jsme byli požádáni o jeji přestavbu na digitální přístroj. Pro komoru bylo nutné navrhnout a vyrobit korekční člen pro narovnání její ohniskové plochy a dále ji vybavit vhodným digitálním fotografickým přístrojem. V této práci přinášíme popis úpravy tohoto přístroje. The Maksutov chamber with a diameter of 350 mm and a focal length of 840 mm was manufactured in Turnov in the early 1980s. At the Úpice Observatory it was used to photograph the sky for photographic film. Currently, we have been asked to convert it to a digital device. It was necessary to design and manufacture a correction element for the chamber to straighten its focal surface and to equip it with a suitable digital camera. In this work we present description of modification of this device. Keywords: Maksutov chamber; focal surface Available at various institutes of the ASCR
Digitalizace Maksutovovy komory 350/840 úpické observatoře

Maksutovova komora o průměru 350 mm a ohniskové vzdálenosti 840 mm byla vyrobena v Turnově počátkem 80. let. Na úpické observatoři sloužila k fotografování oblohy na fotografický film. V současné době ...

Rail, Zdeněk; Melich, Zbyněk
Ústav fyziky plazmatu, 2019

High temperature corrosion studies of HVOF sprayed coatings in molten sulphate salts environment
Lencová, K.; Česánek, Z.; Houdková, Š.; Lukáč, František; Mušálek, Radek
2019 - English
The generally applied requirements on lowering of emission production in the field of power industry have led, among others, into the application of low-emission combustion process of coal fired power plants. Besides the emissions reduction, this process has led to an increase of boilers parts corrosion degradation due to the reducing atmosphere in low-emission boilers, responsible for sulphide corrosion and molten salt attack. In such environment, the protection of the exposed surfaces gains importance. Among others, the thermal spraying technology can offer a suitable way of surface corrosion protection. In the present work, the high temperature corrosion behaviour of CoCrAlYTaCSi and Cr3C2-25%NiCr High Pressure/High Velocity Oxygen Fuel (HP/HVOF) sprayed coatings is evaluated and compared to the behaviour of bare structural steel (SPT360) substrate. The specimens were exposed to a molten salt environment, i. e., 12% Na2SO4 + 82% Fe2(SO4)3 at 690 °C under cyclic condition, simulating the working environment in low-emission boilers of coal-fired power plants. The thermogravimetric method was used to establish the kinetics of corrosion. X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) techniques were used to analyse the corrosion products and determine the corrosion mechanism. The thermogravimetric measurement shows high oxidation rate of SPT360 steel. Cr3C2-25%NiCr coating provides slightly better performance compared to CoCrAlYTaCSi coating. Based on the obtained results, both coatings were found to have higher corrosion resistance than the SPT360 steel substrate, offering a sufficient surface protection in a given environment. Keywords: Coal fired boilers; CoCrAlYTaCSi; Cr3C2-25%NiCr; High temperature corrosion; hvof; Low-emission boilers; Thermal spraying Fulltext is available at external website.
High temperature corrosion studies of HVOF sprayed coatings in molten sulphate salts environment

The generally applied requirements on lowering of emission production in the field of power industry have led, among others, into the application of low-emission combustion process of coal fired power ...

Lencová, K.; Česánek, Z.; Houdková, Š.; Lukáč, František; Mušálek, Radek
Ústav fyziky plazmatu, 2019

Několik návrhů mimoosových optických soustav
Rail, Zdeněk; Franců, Helena; Ulrichová, Iva; Šípová, Gabriela; Vápenka, David; Vávra, Emil
2019 - Czech
Tento referát seznamuje čtenáře s několika typy optimalizovaných mimoosových zrcadlových soustav. Soustavy bez centrálního stínění a barevné vady poskytují zobrazení\ns vysokým kontrastem obrazu. Jsou vhodné pro využití jako dalekohledy pro astronomická pozorování nebo jako přesné laboratorní kolimátory paralelních svazků světla. Řada těchto přístrojů byla navržena a zkonstruována pro nejrůznější účely ve Vývojové optické dílně AVČR, dnes ÚFP AV ČR v.v.i.- Centru Toptec v Turnově.Tato práce seznamuje čtenáře s několika z nich. This paper introduces several types of optimized off-axis mirror systems. Systems without central shading and color defects provide high-contrast imaging. They are suitable for use as astronomical telescopes or as precision laboratory collimators of parallel light beams. Many of these devices have been designed and constructed for various purposes in the Development Optical Workshop of the Academy of Sciences of the Czech Republic. Keywords: Off-axis optical system; astigmatism; spherochromatic aberration; coma; field curvature Available at various institutes of the ASCR
Několik návrhů mimoosových optických soustav

Tento referát seznamuje čtenáře s několika typy optimalizovaných mimoosových zrcadlových soustav. Soustavy bez centrálního stínění a barevné vady poskytují zobrazení\ns vysokým kontrastem obrazu. Jsou ...

Rail, Zdeněk; Franců, Helena; Ulrichová, Iva; Šípová, Gabriela; Vápenka, David; Vávra, Emil
Ústav fyziky plazmatu, 2019

Zbytkové optické vady objektivu Merz 108/1620 mm
Rail, Zdeněk; Melich, Zbyněk; Vápenka, David; Šrajer, Bohdan
2019 - Czech
Během čištění a seřizování Merzova objektivu o průměru 108 mm a ohniskové vzdálenosti 1620 mm jsme měli příležitost proměřit jeho optické parametry. Z naměřených hodnot jsme provedli výpočet zbytkových optických vad tohoto achromatického objektivu. Výsledky těchto matematických simulací přinášíme v tomto referátu. Objektiv byl vyroben okolo roku 1923. During the cleaning and adjustment of the Merz lens with a diameter of 108 mm and a focal length of 1620 mm, we had the opportunity to measure its optical parameters. From the measured values we made a calculation of residual optical defects of this achromatic lens. The results of these mathematical simulations are presented in this paper. The lens was made around 1923. Keywords: Achromatic dublet; aplanat; spherochromatic aberration; coma Available at various institutes of the ASCR
Zbytkové optické vady objektivu Merz 108/1620 mm

Během čištění a seřizování Merzova objektivu o průměru 108 mm a ohniskové vzdálenosti 1620 mm jsme měli příležitost proměřit jeho optické parametry. Z naměřených hodnot jsme provedli výpočet ...

Rail, Zdeněk; Melich, Zbyněk; Vápenka, David; Šrajer, Bohdan
Ústav fyziky plazmatu, 2019

Fluctuations in the scrape-off layer and edge plasma of the COMPASS tokamak
Seidl, Jakub; Jiráková, Kateřina; Adámek, Jiří; Grover, Ondřej; Horáček, Jan; Hron, Martin; Vondráček, Petr
2018 - English
We have identified two distinct types of turbulent fluctuations in COMPASS plasmas, the high-frequency edge oscillations and low-frequency SOL blobs. The transition region is localized in the near SOL, where both types spatially overlap and interact and the radial particle transport gradually transfers from high to low frequencies. Even though skewness of isat fluctuations is positive even inside LCFS, distinguishable Gamma-distributed PDF, formed by the low-frequency fluctuations, arises in the near SOL. This supports, together with turbulence spreading rate being positive in the near SOL but negative in the edge, the picture presented in [3] that most of the fluctuations that form a positive skewness in the edge region disappear around LCFS and new blobs are formed in the near SOL. Further, we cannot confirm the assumption that the blobs are generated randomly according to a Poisson process. Oscillations of all measured quantities, incl. radial particle flux, in the near SOL are peaked around ∼13 kHz. This seems to correspond to a poloidally rotating structure with a rather large poloidal wave-length ∼ 15 − 20 cm, that at least partly modulates blob generation. Nevertheless, we note that time separation of blobs becomes more random further in the SOL, possibly due to differences in their individual propagation. These observations hold for diverted plasmas, but the situation may be different in limited low-elongation plasmas where the radius of zero skewness was observed to be shifted significantly (several cm) inwards, compared to diverted configuration, and Gamma-like PDF is detected even inside the LCFS. Study of these plasmas is ongoing. Keywords: plasma; tokamak; turbulence Fulltext is available at external website.
Fluctuations in the scrape-off layer and edge plasma of the COMPASS tokamak

We have identified two distinct types of turbulent fluctuations in COMPASS plasmas, the high-frequency edge oscillations and low-frequency SOL blobs. The transition region is localized in the near ...

Seidl, Jakub; Jiráková, Kateřina; Adámek, Jiří; Grover, Ondřej; Horáček, Jan; Hron, Martin; Vondráček, Petr
Ústav fyziky plazmatu, 2018

Využití holografie pro měření a charakterizaci povrchu
Kaván, František
2018 - Czech
Tento výzkum je zaměřen na využití digitální holografie pro měření tvaru optických a jiných ploch. Pro první experimenty jsme použili standardní metodu dvojvlnné holografické interferometrie. Ta posloužila jako reference. Hlavním zaměřením je však Frequency Sweeping Digital Holography (FSDH) neboli skenovací digitální holografie, která využívá plynule přeladitelných DFB laserových diod. Přesnost této metody lze dále vylepšit spojením měření z více vlnových délek - více diod. Při spojení je možno pomocí této metody dosáhnout přesnosti až 2 µm. This research focuses on the use of digital holography for measuring the shape of optical and other surfaces. For the first experiments, we used a standard double-wave holographic interferometry method. This served as a reference. However, the main focus is Frequency Sweeping Digital Holography (FSDH), or scanning digital holography, which utilizes fluently translatable DFB laser diodes. The accuracy of this method can be further improved by combining measurements from multiple wavelengths - multiple diodes. When combined, this method can achieve accuracy of up to 2 μm. Keywords: holography; measurement Fulltext is available at external website.
Využití holografie pro měření a charakterizaci povrchu

Tento výzkum je zaměřen na využití digitální holografie pro měření tvaru optických a jiných ploch. Pro první experimenty jsme použili standardní metodu dvojvlnné holografické interferometrie. Ta ...

Kaván, František
Ústav fyziky plazmatu, 2018

Effect of sintering temperature on microstructure and mechanical properties of AE42 magnesium alloy prepared by spark plasma sintering
Minárik, P.; Lukáč, František; Cinert, Jakub; Šašek, S.; Král, R.
2018 - English
Magnesium alloy AE42 was prepared by powder metallurgy technique of spark plasma sintering. The effect of sintering parameters, particularly sintering temperature, on the microstructure and mechanical strength was investigated. The gas-atomized powder was sintered at four temperatures in the temperature range of 400-550 °C. It was found that mechanical strength of the sintered samples was significantly affected by several microstructural features. Application of relatively high load during sintering caused deformation of the individual particles and consequent recrystallization depending on the processing temperature resulted in the release of internal strain and in grain growth. As a result, the evolution of the mechanical strength as a function of the sintering temperature was significantly affected by residual stress, grain size and coarsening of secondary phase particles. Keywords: Magnesium; Mechanical properties; Microstructure; Spark plasma sintering Available at various institutes of the ASCR
Effect of sintering temperature on microstructure and mechanical properties of AE42 magnesium alloy prepared by spark plasma sintering

Magnesium alloy AE42 was prepared by powder metallurgy technique of spark plasma sintering. The effect of sintering parameters, particularly sintering temperature, on the microstructure and mechanical ...

Minárik, P.; Lukáč, František; Cinert, Jakub; Šašek, S.; Král, R.
Ústav fyziky plazmatu, 2018

OLGA – efficient full wave code for the coupling of LH grills
Preinhaelter, Josef; Hillairet, J.; Urban, Jakub
2018 - English
The full wave code OLGA, for determining the coupling of a single row lower hybrid launcher (waveguide grills) to the plasma, is extended to handle multirow multijunction active passive structures (like the C3 and C4 launchers on TORE SUPRA) by implementing the scattering matrix formalism. The extended code is still computationally fast because of the use of (i) 2D splines of the plasma surface admittance in the accessibility region of the k-space, (ii) high order Gaussian quadrature rules for the integration of the coupling elements and (iii) utilizing the symmetries of the coupling elements in the multiperiodic structures. The extended OLGA code is benchmarked against the ALOHA-1D, ALOHA-2D and TOPLHA codes for the coupling of the C3 and C4 TORE SUPRA launchers for several plasma configurations derived from reflectometry and interferometery. Unlike nearly all codes (except the ALOHA-1D code), OLGA does not require large computational resources and can be used for everyday usage in planning experimental runs. In particular, it is shown that the OLGA code correctly handles the coupling of the C3 and C4 launchers over a very wide range of plasma densities in front of the grill. Keywords: lower hybrid waves; coupling; large multirow multijunction grills; tokamak; full-wave Fulltext is available at external website.
OLGA – efficient full wave code for the coupling of LH grills

The full wave code OLGA, for determining the coupling of a single row lower hybrid launcher (waveguide grills) to the plasma, is extended to handle multirow multijunction active passive structures ...

Preinhaelter, Josef; Hillairet, J.; Urban, Jakub
Ústav fyziky plazmatu, 2018

Electric probe measurements in the anode area of a DC arc plasma torch at low pressure
Ondáč, Peter; Mašláni, Alan; Hrabovský, Milan
2018 - English
We measured radial profiles of the electric field, plasma electrical potential and electron temperature in the hot anode area of a hybrid water-argon DC arc plasma torch with an external anode. The measurements were made under different values of the ambient pressure, during the restrike mode with a constricted anode arc attachment or during a supersonic mode with a diffuse anode arc attachment. The results provide first experimental data on plasma electrical potential in that anode area. Keywords: plasma; arc; anode; low pressure; electric probes Available at various institutes of the ASCR
Electric probe measurements in the anode area of a DC arc plasma torch at low pressure

We measured radial profiles of the electric field, plasma electrical potential and electron temperature in the hot anode area of a hybrid water-argon DC arc plasma torch with an external anode. The ...

Ondáč, Peter; Mašláni, Alan; Hrabovský, Milan
Ústav fyziky plazmatu, 2018

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