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XUV Spectra from High Current Nitrogen Z-Pinch Capillary Discharge.
Vrba, Pavel; Vrbová, M.
2017 - English
We have performed computer modeling of the pinching plasma of capillary discharge using the 1d NPINCH code, that considers ablation of the capillary wall. At high currents we have observed that, the ablation has significant effect on the plasma electron temperature evolution and on the rate of pinch decay. To estimate the emitted spectra in XUV range, the FLYCHK code was used as a post processor. The capillary wall ablation represents the principal obstacles of recombination pumping during pinch decay.\n
Keywords:
MHD and RMHD simulations of high current capillary discharge; Z-pinches; water window radiation; capillary wall ablation
Available at various institutes of the ASCR
XUV Spectra from High Current Nitrogen Z-Pinch Capillary Discharge.
We have performed computer modeling of the pinching plasma of capillary discharge using the 1d NPINCH code, that considers ablation of the capillary wall. At high currents we have observed that, the ...
The investigation of an Al-Zr-Ti alloy prepared by spark plasma sintering of atomized powder
Molnárová, O.; Málek, P.; Lukáč, František; Chráska, Tomáš; Cinert, Jakub
2017 - English
The microstructure and mechanical properties of a powder metallurgical Al-Zr-Ti alloy was studied. Fine powder with a typical size below 50 ?m was prepared by gas atomization. The smallest powder particles with a diameter below 10 ?m exhibited a segregation free microstructure. Larger droplets were found to contain intermetallic particles rich in Zr and Ti. The gas atomized powder was consolidated by spark plasma sintering (SPS) at various temperatures ranging from 450 to 550 °C. During SPS the materials microstructure remained nearly unchanged and a fine grain size between 2 and 3 ?m was observed. All SPS samples exhibited a microhardness of around 90 HV. The annealing (1 h, 500 °C) of the sample sintered at the highest temperature (550 °C) resulted in a decrease of microhardness to 75 HV as a result of changes in the phase composition, the fine grain size was retained. Natural aging at room temperature was not observed.
Keywords:
Gas atomization; High strength alloy; Spark plasma sintering; Thermal stability
Available at various institutes of the ASCR
The investigation of an Al-Zr-Ti alloy prepared by spark plasma sintering of atomized powder
The microstructure and mechanical properties of a powder metallurgical Al-Zr-Ti alloy was studied. Fine powder with a typical size below 50 ?m was prepared by gas atomization. The smallest powder ...
Surface profilometry by digital holography
Psota, Pavel; Lédl, Vít; Kaván, František; Matoušek, O.; Mokrý, P.
2017 - English
This paper presents newly developed method for measurement of surface topography based on frequency scanning digital holography. Digital holography allows for direct computation of the phase field of the wavefront scattered by an object. A tuning of the light source optical frequency results in linear phase variation with respect to the optical frequency. Slope of the linear function in every single pixel corresponds to absolute measurement of optical path difference and thus topography map of the surface can be retrieved. Principle of this contactless method is introduced and experimentally verified. The method can be used for measurement of complex geometries of common manufacturing parts as well as for topography measurement of complex composite structures, and active acoustic metasurfaces.
Keywords:
Surface profilometry; Digital holography; Frequency scanning; Absolute measurement
Available at various institutes of the ASCR
Surface profilometry by digital holography
This paper presents newly developed method for measurement of surface topography based on frequency scanning digital holography. Digital holography allows for direct computation of the phase field of ...
Mechanical properties of plasma sprayed layers of NiAl10 and NiAl40 on AZ91 alloy
Kubatík, Tomáš František; Brodil, R.; Ctibor, Pavel; Průša, F.; Brožek, Vlastimil
2017 - English
In this work, plasma coatings of NiAl10 and NiAl40 on magnesium alloy AZ91 substrate were prepared by the hybrid plasma spraying system WSP®-H 500. The both plasma sprayed coatings of NiAl10 and NiAl40 have metallurgical bond. The thicknesses of microstructures in the cross-section of NiAl10 and NiAl40 plasma sprayed coatings prepared by 9 passes were 374 and 440 μm respectively. Adhesion test of plasma sprayed layers was performed using a modified ASTM C 633 standard. The tensile adhesion strength values are 24.7 MPa for NiAl10 coatings and 12.3 MPa for NiAl40 coatings. Abrasion resistance according to Slurry Abrasion Response (SAR) test of NiAl40 layers had similar values (0.12 g/cm2)in a comparison with the uncoated AZ91 (0.126 g/cm2). Layers NiAl10 had greater weight losses (0.175 g/cm2) than uncoated AZ91. Microhardness of plasma coating of NiAl40 is several times greater than microhardnesses of plasma coating of NiAl10 and uncoated substrate AZ91
Keywords:
Adhesion strength; Nickel alloys; Plasma spraying; Wear resistance
Available at various institutes of the ASCR
Mechanical properties of plasma sprayed layers of NiAl10 and NiAl40 on AZ91 alloy
In this work, plasma coatings of NiAl10 and NiAl40 on magnesium alloy AZ91 substrate were prepared by the hybrid plasma spraying system WSP®-H 500. The both plasma sprayed coatings of NiAl10 and ...
Large displacement and deformation measurement by frequency sweeping digital holography
Psota, P.; Lédl, Vít; Kaván, František; Matoušek, O.; Doleček, R.
2017 - English
Recently, a digital holographic method called Frequency Sweeping Digital Holography (FSDH) for high precision measurements of surface topography of mechanical parts has been introduced. The greatest advantage of the presented FSDH is the fact that the measurement is absolute. i.e. optical path difference is independently retrieved in every single pixel. This approach can therefore be used also for measurement of large displacements and deformation. FSDH is particularly suitable in cases where the common digital holographic methods fail due to e.g. 2π unambiguity problem or speckle decorrelation. Measurement method principles, setup details, an some features of the method are discussed.\n
Keywords:
Digital holography; Digital holographic interferometry; Displacement measurement; Absolute measurements
Available at various institutes of the ASCR
Large displacement and deformation measurement by frequency sweeping digital holography
Recently, a digital holographic method called Frequency Sweeping Digital Holography (FSDH) for high precision measurements of surface topography of mechanical parts has been introduced. The greatest ...
Virtuální zobrazení vzdálených objektů dlouhofokálními spojkami a konkávními zrcadly
Rail, Zdeněk; Vápenka, David
2016 - Czech
Dlouhofokální spojky a konkávní zrcadla mohou sloužit jako optické prvky, úhlově zvětšující rozměry vzdálených objektů podobně jako dalekohledy. Tyto jejich vlastnosti mohly být pravděpodobně používány pozorovateli dávno před objevem dalekohledu. Naše práce přináší optickou analýzu a výsledky astronomických pozorování soustavou dlouhofokální positivní čočky a lidského oka. The longfocal positive lenses and concave mirrors can serve as optical elements increasing the angular dimensions of the distant objects similarly to telescope.\nThese properties could be probably used by ancient observers before the discovery of telescope.\nOur paper brings optical analysis and results of visual astronomical observations with the longfocal positive lens.
Keywords:
Real and virtual imaging; Angular magnification; Ibn al-Haytham; Benjamin of Tudela; Roger Bacon; Giambattista della Porta; Johann Lippershey; Galileo; Kepler; Longfocal lens; Lighthouse on Pharos island; Ancient lenses; Šolc mirror; Camera obscura; Longfocal lens observation
Available at various institutes of the ASCR
Virtuální zobrazení vzdálených objektů dlouhofokálními spojkami a konkávními zrcadly
Dlouhofokální spojky a konkávní zrcadla mohou sloužit jako optické prvky, úhlově zvětšující rozměry vzdálených objektů podobně jako dalekohledy. Tyto jejich vlastnosti mohly být pravděpodobně ...
Black Chromia Plating for the Solar Radiation Absorbers
Brožek, Vlastimil; Březina, Václav; Brom, Petr; Kubatík, Tomáš František; Vilémová, Monika; Mastný, L.; Novák, M.
2016 - English
Black chromia layers were produced on copper, zirconium and aluminium substrates. These layers are aimed to serve as solar collectors. Efficiency of the layers during UV-VIS, UV radiation and WSP® plasma torch radiation is described. The chromia layers were prepared by a new procedure, i.e. deposition of ammonium dichromate solution using plasma torch or so called Liquid Precursor Plasma Spraying (LPPS). Solution of ammonium dichromate is fed into plasma stream, where dissociation takes place under temperatures of 4000 K – 25000 K. Up to nanometric oxide particles can be produced; the resulting size is dependent on solution concentration and feeding nozzle diameter. The particles impact on substrate and form coating. Using 2 wt.% to 5 wt.% solution of ammonium dichromate and feeding nozzle of 0.2 mm in diameter is the size of produced chromia particles about 6 µm which results in formation of 2 µm to 3 µm thick coating, i.e. according to the theory an optimal thickness 2.5 um for absorption layers, necessary condition for formation energy traps for IR radiation emitters up to 100°C. Moreover, black chromia coating is a suitable corrosion barrier of metallic substrates. \n\n
Keywords:
Solar collector; black chromia; plasma spraying; ceramic coatings
Available at various institutes of the ASCR
Black Chromia Plating for the Solar Radiation Absorbers
Black chromia layers were produced on copper, zirconium and aluminium substrates. These layers are aimed to serve as solar collectors. Efficiency of the layers during UV-VIS, UV radiation and WSP® ...
Black Chromia Coatings on Metal Tubes for the Solar Collectors
Brožek, V.; Mastný, L.; Novák, M.; Vilémová, Monika; Kubatík, Tomáš František
2016 - English
This paper describes the results of the first phase of the study preparation, structure and properties of coatings modification of black chromium oxide on copper, aluminium, iron and zirconium tubes for solar collectors. The coatings are prepared by plasma spraying of liquid chromate method which is known as liquid precursor plasma spraying. Coatings have the function of an energy trap for thermal radiation wavelengths of 1 μm – 3 μm i.e. in the IR region. At the same time, the coating increases the corrosion resistance of metal substrates. The nanometric structure and thickness of the coating depend of the feeding distance and the concentration of chromate precursors. For the deposition of nanometric splats of melt chromiumIII oxide, a new type of feeder that injects precursors into the water stabilized thermal plasma produced by the WSP® generator has been\ndeveloped.\n
Keywords:
Solar collector; black chromia; plasma spraying; suspension spraying
Available at various institutes of the ASCR
Black Chromia Coatings on Metal Tubes for the Solar Collectors
This paper describes the results of the first phase of the study preparation, structure and properties of coatings modification of black chromium oxide on copper, aluminium, iron and zirconium tubes ...
Spectroscopic Study of Underwater Electrical Discharge Generated by Nanosecond Pulses.
Pongrác, Branislav; Šimek, Milan; Babický, Václav; Člupek, Martin; Lukeš, Petr
2016 - English
Underwater electrical discharge generated by high voltage pulses with nanosecond duration (~110 kV amplitude on the needle, ~5 ns duration (FWHM), 1 Hz repetition rate) has been investigated. Time–resolved optical emission spectroscopy showed different emission spectra profile of the ns–pulsed discharge compared to the μs–pulsed discharges investigated previously. Some characteristic peaks typical for water discharges (Hα, OI) were clearly visible in the spectra. In addition, the integral light emission of the discharge was recorded by photomultiplier tube.
Keywords:
nanosecond discharge; water discharge; time-resolved emission spectroscopy
Available at various institutes of the ASCR
Spectroscopic Study of Underwater Electrical Discharge Generated by Nanosecond Pulses.
Underwater electrical discharge generated by high voltage pulses with nanosecond duration (~110 kV amplitude on the needle, ~5 ns duration (FWHM), 1 Hz repetition rate) has been investigated. ...
Gap – gep – mezera?
Obdržálek, J.; Bílková, Petra; Mlynář, Jan
2016 - Czech
Jsou prezentovány obecné terminologické obtíže v odborném jazyce fyziky kontinua. Zvláště se příspěvek zabývá výhodami a nevýhodami velkého vlivu angličtiny z hlediska grafického (typologického) a fonetického. They presented the general terminological difficulties in technical language continuum physics. In particular it deals with the advantages and disadvantages of the great influence of English in terms of graphical (typological) and phonetic
Keywords:
phonetics; typology
Available at various institutes of the ASCR
Gap – gep – mezera?
Jsou prezentovány obecné terminologické obtíže v odborném jazyce fyziky kontinua. Zvláště se příspěvek zabývá výhodami a nevýhodami velkého vlivu angličtiny z hlediska grafického (typologického) a ...
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