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Ceramo-metallic materials of the Ti-B-C and Ti-B-N systems
Brožek, V.; Doležal, J.; Novák, M.; Ctibor, Pavel; Kolman, Blahoslav Jan
2011 - anglický
Products prepared by the sintering of titanium and boron carbide powder and by the sintering of titanium and boron nitride powder were studied. The sintering was performed at 2,000 °C under the pressure of 6 GPa in a high-pressure apparatus of BELT-type with sufficient holding time to reach thermodynamic equilibrium. The results of chemical and phase composition analyses were compared with thermodynamic prediction of possible reactions in the system. We proved the preferential formation of borides TiB and TiB2 prior to the carbides or nitrides formation. The products, which may be considered Ti-(TiB,TiB2)-TiN or Ti-(TiB,TiB2)-TiC cermets, were analysed in order to determine their microstructure, phase and chemical composition and their influence on mechanical properties such as hardness or elastic modulus. This work precedes similar study which will be performed using the same powders processed by plasma spraying, which enables to stabilize high-temperature phases by rapid cooling.
Klíčová slova:
Hot pressing; reactive sintering; titanium boride; titanium nitride; boron carbide; plasma spraying
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Ceramo-metallic materials of the Ti-B-C and Ti-B-N systems
Products prepared by the sintering of titanium and boron carbide powder and by the sintering of titanium and boron nitride powder were studied. The sintering was performed at 2,000 °C under the ...
Measurements of Ion Temperature in the Edge Plasma of the COMPASS Tokamak
Naydenkova, Diana; Janky, Filip; Weinzettl, Vladimír; Stöckel, Jan; Šesták, David; Odstrčil, T.; Ghosh, J.; Gomes, R.; Pereira, T.
2011 - anglický
The two-grating spectrometer, which has been developed for the ISTTOK tokamak, allows an estimation of the temporal evolution of both ion temperature and poloidal velocity of the edge plasma by analysis of Doppler-shifted and broadened CIII spectral lines at ~465nm. At the current phase of the COMPASS tokamak operation, the first measurements of ion temperature using the optical system based on the spectrometer were performed and first results are presented.
Klíčová slova:
COMPASS; tokamak; Ion Temperature; Edge Plasma
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Measurements of Ion Temperature in the Edge Plasma of the COMPASS Tokamak
The two-grating spectrometer, which has been developed for the ISTTOK tokamak, allows an estimation of the temporal evolution of both ion temperature and poloidal velocity of the edge plasma by ...
Application of Pulsed Electric Field on Bacteria
Kadlec, Tomáš; Babický, Václav; Člupek, Martin; Vrbová, M.
2011 - anglický
Electrical discharges in a water solution cause several processes. e.g., generation of UV radiation, free radicals, and a shockwave, pulse electric field (PEF) takes place too. The PEF was studied separately to achieve better understanding of this complex process. PEF treatment is chemical-free process affecting microbes. An experimental device for PEF treatment was constructed. Solution containing microbial culture of Bacillus subtilis was treated.
Klíčová slova:
Pulsed Electric Field; Bacteria
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Application of Pulsed Electric Field on Bacteria
Electrical discharges in a water solution cause several processes. e.g., generation of UV radiation, free radicals, and a shockwave, pulse electric field (PEF) takes place too. The PEF was studied ...
Characterization of fluctuating discharge
Chumak, Oleksiy; Hrabovský, Milan
2011 - anglický
A digital camera coupled with computer has a great potential in an analysis of discharges structures. This work analyzes an approach to visualization of dynamic radiant object. Mapping of brightness uncertainty values is used to show regions of different fluctuation intensity of radiation. The entropy as described by information theory was used as a relevant parameter for an uncertainty value. By a mathematical procedure a relative parameter based on the entropy was evaluated. As result an effects of optics sensitivity or of imperfections of experimental set-up were significantly suppressed.
Klíčová slova:
Plasma stability; jet fluctuations; statistical processing; entropy maps
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Characterization of fluctuating discharge
A digital camera coupled with computer has a great potential in an analysis of discharges structures. This work analyzes an approach to visualization of dynamic radiant object. Mapping of brightness ...
A Simulation of the COMPASS Equilibrium Field Power Supply PID Controller
Havlíček, Josef; Beňo, Radek; Stöckel, Jan
2011 - anglický
The COMPASS tokamak Magnetizing Field (MFPS) and Equilibrium Field Power Supplies (EFPS) circuits are coupled together by mutual inductance and by shared coil in the tokamak central solenoid. EFPS controller has problems with mitigating the voltage distortion caused by MFPS. A modelling was used to obtain better understanding of the system and to improve the EFPS controller algorithm.
Klíčová slova:
tokamak; Power Supply; COMPASS; PID controller
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
A Simulation of the COMPASS Equilibrium Field Power Supply PID Controller
The COMPASS tokamak Magnetizing Field (MFPS) and Equilibrium Field Power Supplies (EFPS) circuits are coupled together by mutual inductance and by shared coil in the tokamak central solenoid. EFPS ...
Measurement of the Laser Beam Position and Width for the Thomson Scattering Diagnostics on Tokamak COMPASS
Aftanas, Milan; Bílková, Petra; Böhm, Petr; Weinzettl, Vladimír; Stöckel, Jan; Hron, Martin; Pánek, Radomír
2011 - anglický
COMPASS tokamak is equipped with new key diagnostic—Thomson scattering system. This unique multi-point system has been designed with the main aim to investigate electron density and temperature profiles on the COMPASS tokamak (R = 0.56 m, a = 0.18 m, BT max = 2.1 T). The spatial resolution is optimized namely for the pedestal studies (radial spatial resolution a/100). This contribution describes particular steps of optical alignment of the important part of the Thomson scattering system, Nd:YAG lasers (1.6 J at 1064 nm, 30 Hz). Laser beam width has to be precisely measured and laser beam position has to be precisely set before the measurement and checked for all laser shots to be able of decrypting the information about the plasma density and also to improve precision of the measurement. New tool for automatic measurement of the laser beam misalignment is introduced.
Klíčová slova:
plasma diagnostics; Tokamak devices
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Measurement of the Laser Beam Position and Width for the Thomson Scattering Diagnostics on Tokamak COMPASS
COMPASS tokamak is equipped with new key diagnostic—Thomson scattering system. This unique multi-point system has been designed with the main aim to investigate electron density and temperature ...
Simulations of Runaway Electrons
Papřok, R.; Krlín, Ladislav; Cahyna, Pavel
2011 - anglický
In this paper we discuss current knowledge of phenomena of runaway electrons in tokamaks. We summarize experimental facts and investigate theoretical understanding of runaway electrons. We also present result of our recent work concerning influence of JET’s Error Filed Correction Coils on runaway electrons dynamics. At the end of our paper we describe our plan to study runaway electrons dynamic in time and space varying magnetic field during plasma disruption as obtained from global MHD code JOREK.
Klíčová slova:
Runaway electron simulation; plasma
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Simulations of Runaway Electrons
In this paper we discuss current knowledge of phenomena of runaway electrons in tokamaks. We summarize experimental facts and investigate theoretical understanding of runaway electrons. We also ...
Numerical simulations of jet formation in laser-target interactions
Váchal, P.; Liska, R.; Kuchařík, M.; Limpouch, J.; Kmetík, Viliam
2010 - anglický
Cylindrical version of our two-dimensional Arbitrary Lagrangian Eulerian code PALE is applied for numerical studies of dense plasma jet formation from laser targets. Well collimated plasma expansion from a massive solid target irradiated by a single laser beam with a special profile is investigated. Particular interaction beam profile with intensity minimum in the beam centre is found to be responsible for jet formation during plasma expansion. A deep concave interaction beam profile at PALS is obtained from our simulation of the laser propagation in the amplifying chain and in the focusing system.
Klíčová slova:
laser plasma; plasma jet
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Numerical simulations of jet formation in laser-target interactions
Cylindrical version of our two-dimensional Arbitrary Lagrangian Eulerian code PALE is applied for numerical studies of dense plasma jet formation from laser targets. Well collimated plasma expansion ...
Experimental investigation of electric arc behavior during cutting of stainless steel
Kavka, Tetyana; Mašláni, Alan; Konrád, Miloš; Tossens, S.
2010 - anglický
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.
Klíčová slova:
DC arc; plasma cutting; anode attachment
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Experimental investigation of electric arc behavior during cutting of stainless steel
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 ...
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
2010 - anglický
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.
Klíčová slova:
corona discharge; ultraviolet radiation; E.coli; E. faecalis
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Role of UV radiation, solution conductivity and pulse repetition frequency in the bactericidal effects during pulse corona discharge in water
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 ...
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