Number of found documents: 589
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Relativistic effects in plasma produced with sub-nanosecond 3-TW laser
Krása, J.; Klír, Daniel; Řezáč, Karel; Cikhardt, Jakub; Krůs, Miroslav; Velyhan, Andriy; Pfeifer, Miroslav; Dostál, Jan; Dudžák, Roman; Krupka, Michal; Kaufman, J.; Pisarczyk, T.; Kalinowska, Z.; Chodukowski, T.
2018 - English
This contribution deals with observations of relativistic electrons produced in a laser plasma interaction experiment at the PALS laser system operated at the Institute of Plasma Physics in Prague. The PALS laser is a near-infrared 3-TW iodine laser designed to deliver irradiance on target of 1016 Wcm2- in≈300 ps pulses at the wavelength of 1.315 μm. Various foils of 6 500 μm in thickness were irradiated with Iλ2 ≈5×1016 W cm-2 μm2 Under these conditions we have observed relativistic electrons expanding into the vacuum with maximum energy going beyond 4 MeV. The relativistically accelerated forward electrons escaping from the rear target surface were observed with the use of electron energy analysers. The observed electron energy spectra indicate that the applied laser intensity was increased by the thermal and relativistic self-focusing. The application of a unique femtosecond interferometry technique allowed us to observe bunches of thermal electrons occurring in the plasma expanding against the focused laser beam. Keywords: laser-produced plasma; relativistic electrons Fulltext is available at external website.
Relativistic effects in plasma produced with sub-nanosecond 3-TW laser

This contribution deals with observations of relativistic electrons produced in a laser plasma interaction experiment at the PALS laser system operated at the Institute of Plasma Physics in Prague. ...

Krása, J.; Klír, Daniel; Řezáč, Karel; Cikhardt, Jakub; Krůs, Miroslav; Velyhan, Andriy; Pfeifer, Miroslav; Dostál, Jan; Dudžák, Roman; Krupka, Michal; Kaufman, J.; Pisarczyk, T.; Kalinowska, Z.; Chodukowski, T.
Ústav fyziky plazmatu, 2018

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
In this work we study properties of turbulent structures in the scrape-off layer (SOL) and edge plasma of the COMPASS tokamak. Two distinct types of coherent oscillations are observed: a) broadband high frequency branch rotating in the electron diamagnetic direction, appearing mainly in the confined region but protruding also to the SOL b) low-frequency blobs rotating in an opposite poloidal direction, formed in the vicinity of the radius of zero electric field. 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 fluctuations of the ion saturation current is positive even inside LCFS, distinguishable Gamma-distributed PDF, formed by the low-frequency fluctuations, arises in the near SOL and most of the fluctuations that form a positive skewness in the edge region disappear around LCFS. Keywords: plasma; tokamak; turbulence Fulltext is available at external website.
Fluctuations in the scrape-off layer and edge plasma of the COMPASS tokamak

In this work we study properties of turbulent structures in the scrape-off layer (SOL) and edge plasma of the COMPASS tokamak. Two distinct types of coherent oscillations are observed: a) broadband ...

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

Optický element pro dopravní tabule 2G25 varA
Pintr, Pavel
2018 - Czech
Výzkumná zpráva popisuje vývoj a měření optiky pro dopravní informační tabule označenou jako 2G25 varA. První část zprávy popisuje vývoj kolimovaného svazku a tvorbu obdélníkového spotu dle požadavků normy ČSN EN 12966. Druhá část zprávy popisuje provedená optická měření. The optical element 2G25 varA is designed according the specification ČSN EN 12966 class B6 for traffic marking. The front optical lens is freeform optics with polynomial coefficients. This element uses RGB LED for mixing white light. Keywords: optical element; freeform; ČSN EN 12966 Available at various institutes of the ASCR
Optický element pro dopravní tabule 2G25 varA

Výzkumná zpráva popisuje vývoj a měření optiky pro dopravní informační tabule označenou jako 2G25 varA. První část zprávy popisuje vývoj kolimovaného svazku a tvorbu obdélníkového spotu dle požadavků ...

Pintr, Pavel
Ústav fyziky plazmatu, 2018

The role of microstructure on wettability of plasma sprayed yttria stabilized zirconia coatings
Komarov, P.; Čelko, L.; Remešová, M.; Skorokhod, K.; Jech, D.; Klakurková, L.; Slámečka, K.; Mušálek, Radek
2018 - English
Atmospheric plasma spraying utilizing initial powder materials in micrometric size has been successfully used for various applications in different fields of the industry over the past several decades. Nowadays, the new trend in plasma spraying is to use sub-micron or nano-sized powder feedstocks in the form of colloidal suspension. This relatively new technology enables to obtain specific types of dense vertically cracked, fully dense or columnar microstructure. The aim of this work is to investigate the influence of coatings microstructure and topography on its water wetting properties. Two different microstructures, i.e. lamellar and columnar, were sprayed from chemically the same yttria-stabillized zirconia (YSZ) ceramics powders by the means of conventional atmospheric plasma spray and suspension hybrid water stabilized plasma spray techniques, respectively. Microstructural and phase composition of the initial powders and as-sprayed coatings were investigated using optical microscopy, scanning electron microscopy and X-ray diffraction techniques. Topography of coatings surface was measured by means of non-contact optical profilometry. The YSZ coatings wettability was evaluated based on water droplet contact angle using Sessile droplet method. The coatings microstructure reveals the important role in the change of droplet contact angle, where lamellar microstructure was found close to hydrophilic-hydrophobic transition and columnar microstructure was found superhydrophobic Keywords: Contact angle; Plasma spraying; Sessile drop method; Water; Yttria stabilized zirconia Available at various institutes of the ASCR
The role of microstructure on wettability of plasma sprayed yttria stabilized zirconia coatings

Atmospheric plasma spraying utilizing initial powder materials in micrometric size has been successfully used for various applications in different fields of the industry over the past several ...

Komarov, P.; Čelko, L.; Remešová, M.; Skorokhod, K.; Jech, D.; Klakurková, L.; Slámečka, K.; Mušálek, Radek
Ústav fyziky plazmatu, 2018

Vývoj optického řešení Prototypu II
Pintr, Pavel
2018 - Czech
Zpráva popisuje vývoj aktivní laserové hlavice. Zpráva je rozdělena do dvou etap. První etapa popisuje vývoj navařovací laserové hlavice s obdélníkovým spotem. Druhá část popisuje vývoj svařovací hlavice s proměnným zvětšením. This report describes the development of an active laser head. This report is separated into two sections. First section describes a development of laser head with the rectangular spot. The second section describes a development of welding laser head with the adaptive zoom. Keywords: laser head; active optics; LIMO Available at various institutes of the ASCR
Vývoj optického řešení Prototypu II

Zpráva popisuje vývoj aktivní laserové hlavice. Zpráva je rozdělena do dvou etap. První etapa popisuje vývoj navařovací laserové hlavice s obdélníkovým spotem. Druhá část popisuje vývoj svařovací ...

Pintr, Pavel
Ústav fyziky plazmatu, 2018

Test procedure - neosted SOT test bench
Pleštil, Jan; Steiger, Lukáš; Václavík, Jan; Veselý, Martin
2018 - English
This document describes the final design of the NEOSTED SOT Test Bench, i.e. its individual components, and serves as a groundwork for the acceptance test procedure.\nThe test to be performed according to this procedure are to demonstrate the compliance of the above item to the requirements specified in the applicable document [1] as part of the overall verification program. The test results shall be collected in a Test Report. Keywords: collimator; optical tests; stage; alignment Available at various institutes of the ASCR
Test procedure - neosted SOT test bench

This document describes the final design of the NEOSTED SOT Test Bench, i.e. its individual components, and serves as a groundwork for the acceptance test procedure.\nThe test to be performed ...

Pleštil, Jan; Steiger, Lukáš; Václavík, Jan; Veselý, Martin
Ústav fyziky plazmatu, 2018

Výzkumná zpráva Projekt MidFree
Beneš, Jiří; Matoušek, Ondřej; Špína, Michal; Tomka, David
2018 - Czech
Výzkumná zpráva popisující model procesního řetězce, metodiky měření a charakterizace středních frekvencí (MSF), vibrací a hodnocení nástrojů. Research report describing the process chain model, MSF measurement methodology, vibration and tool evaluation. Keywords: mid spatial frequencies measurement; vibration measurement Available at various institutes of the ASCR
Výzkumná zpráva Projekt MidFree

Výzkumná zpráva popisující model procesního řetězce, metodiky měření a charakterizace středních frekvencí (MSF), vibrací a hodnocení nástrojů....

Beneš, Jiří; Matoušek, Ondřej; Špína, Michal; Tomka, David
Ústav fyziky plazmatu, 2018

Microstructure of commercially pure titanium after cryogenic milling and spark Plasma sintering
Kozlík, J.; Harcuba, P.; Stráský, J.; Chráska, Tomáš; Janeček, M.
2018 - English
Commercially pure titanium was prepared by advanced powder metallurgy methods with the aim to produce the ultra-fine grained material. Cryogenic attritor milling was used as a first step to refine the microstructure at liquid argon temperatures to suppress recovery and dynamic recrystallization. Spark plasma sintering was subsequently employed to produce bulk material, exploiting its ability to achieve fully dense structure in short time and thus to reduce the grain growth. In order to understand the undergoing microstructural changes during the process, detailed investigation was performed after each preparation step. Powder morphology was changed significantly after milling, while particle fragmentation was only limited. Grain size after sintering was in micrometer scale, relatively independent of sintering conditions. Keywords: Cryogenic milling; Microstructure; Spark plasma sintering; Titanium Available at various institutes of the ASCR
Microstructure of commercially pure titanium after cryogenic milling and spark Plasma sintering

Commercially pure titanium was prepared by advanced powder metallurgy methods with the aim to produce the ultra-fine grained material. Cryogenic attritor milling was used as a first step to refine the ...

Kozlík, J.; Harcuba, P.; Stráský, J.; Chráska, Tomáš; Janeček, M.
Ústav fyziky plazmatu, 2018

Combined coatings against mechanical wear and corrosion low carbon steel
Brožek, Vlastimil; Pokorný, P.; Kolísko, J.; Vokáč, M.; Mastný, L.; Stoulil, J.
2018 - English
In this study, special ceramic coatings were prepared on low carbon steel (1.0060 - EN 10027-2) via the plasma spraying technique using a WSP®-H plasma generator with output of up to 40 kg/h of aluminum oxide. Corundum coatings were deposited directly on the surface of steel plungers equipped with an anti-corrosion interlayer of zinc phosphate. Coating adhesion properties were tested using pin-off tests (modified ISO 4624) and reached a maximum value of 26 MPa. Corrosion resistance was evaluated by measurements of impedance spectra in the 100 kHz - 10 mHz range in a water solution of sodium sulfate. The capacity of electric double-layer varied depending on the porosity and thickness of the coating. Low-porosity coatings of >1.5 mm thickness had RCT 1.29·105 Ω·m2. The abrasive resistance of coatings was measured by rotary/machining test with SiC cutting knives, using a downforce of 50 kg·cm-2. Abrasion losses decreased with the quality of finish - starting at 0.00266 g cm-2 min-1 down to virtually zero losses after polishing the surface below Ra = 0.55 micro m. Keywords: Abrasion; Ceramic coatings; Corrosion resistance; Plasma spraying; Steel phosphating Available at various institutes of the ASCR
Combined coatings against mechanical wear and corrosion low carbon steel

In this study, special ceramic coatings were prepared on low carbon steel (1.0060 - EN 10027-2) via the plasma spraying technique using a WSP®-H plasma generator with output of up to 40 kg/h of ...

Brožek, Vlastimil; Pokorný, P.; Kolísko, J.; Vokáč, M.; Mastný, L.; Stoulil, J.
Ústav fyziky plazmatu, 2018

Suspension plasma spraying of sub-stoichiometric titania by hybrid water/argon stabilized plasma torch
Mušálek, Radek; Ctibor, Pavel; Medřický, Jan; Tesař, Tomáš; Kotlan, Jiří; Lukáč, František
2018 - English
In this study, suspension plasma spraying of sub-stoichiometric titania was attempted using hybrid water/argon stabilized plasma torch (WSP-H). Porous coatings with fine cauliflower-like columnar microstructure were successfully deposited in two separate experiments with different power levels of the plasma torch. In both cases, high solid-load content (40 wt. %) of the water-based suspension resulted in considerable coating thickness increase per deposition cycle. Coating annealing and partial remelting of the surface asperities were also achieved by additional pass of plasma torch in front of the coating surface. According to X-ray diffraction, all coatings consisted dominantly of rutile phase. Detailed microscopic observation of the as-sprayed and annealed deposits showed that the local coloration of the coating (ranging from dark blue to beige) was driven by the local overheating of the rough coating surface which could also promote the oxygen intake. Moreover, sample annealing was also observed to increase the sample reflectivity as observed by UV-VIS-NIR scanning spectrophotometry Keywords: Liquid feedstock; Plasma spraying; Suspension; Thermal spraying; Titania; WSP-H Available at various institutes of the ASCR
Suspension plasma spraying of sub-stoichiometric titania by hybrid water/argon stabilized plasma torch

In this study, suspension plasma spraying of sub-stoichiometric titania was attempted using hybrid water/argon stabilized plasma torch (WSP-H). Porous coatings with fine cauliflower-like columnar ...

Mušálek, Radek; Ctibor, Pavel; Medřický, Jan; Tesař, Tomáš; Kotlan, Jiří; Lukáč, František
Ústav fyziky plazmatu, 2018

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