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Studies of plasma disruptions in the COMPASS tokamak
Matveeva, Ekaterina ; Tichý, Milan (advisor) ; Van Oost, Guido (referee) ; Gerasimov, Sergei (referee)
Title: Studies of plasma disruptions in the COMPASS tokamak Author: Ekaterina Matveeva Department: Department of Surface and Plasma Physics Supervisor: RNDr. Milan Tich'y, Dr.Sc., Univerzita Karlova, Katedra fyziky povrch˚u a plazmatu Abstract: Plasma disruption in a tokamak is an important physical phenomenon, when there is a sudden loss of plasma confinement and rapid drop of plasma current. During the disruptions, there is significant mechanical stress on the construc- tional structures of the tokamak and thermal stress on the first wall. Allowable number of disruptions with the maximum plasma parameters in the ITER toka- mak (international thermonuclear experimental reactor under construction) will be very limited. Therefore, investigation of disruptions and their consequences is a key problem for sustainable operation of tokamak devices. The thesis focuses on studies of current quench phase and related currents flow- ing in the vacuum vessel at the COMPASS tokamak. An extensive disruption database was collected and critical disruptions' parameters were determined. Plasma current was measured at 5 toroidal position as a consequence of data acquisition system improvement that allowed reliable measurements by magnetic coils without analogue integrators. Special divertor tiles were installed in or- der to...
Probe methods for diagnostics of plasmatic systems for deposition of thin films
Zanáška, Michal ; Tichý, Milan (advisor) ; Dvořák, Pavel (referee) ; Straňák, Vítězslav (referee)
The doctoral thesis deals with an experimental study of several diagnostic techniques intended for plasma diagnostics and diagnostics of thin films during reactive sputter deposition. A relatively novel probe diagnostic technique called Floating harmonic probe for measurement of the ion density and electron tem- perature in technological low-temperature plasma is studied. A Langmuir probe is commonly used, however, its application in conditions where non-conducting films are being deposited can be problematic or unreliable. The floating harmonic probe measurement technique deals with this inherent problem of the Langmuir probe. The Floating harmonic probe results are compared to those obtained by a classical Langmuir probe in non-reactive DC continuously driven discharge, and its applicability in reactive regime during deposition of iron oxide thin films is proved. The work deals also with a modification of the Floating harmonic probe called Phase Delay Harmonic Analysis Method which is intended for diagnostics of pulsed driven discharges. The second part of the thesis is devoted to a new proposed method for in-situ diagnostics of thin films. This method monitors the capacitance and resistance of a thin film during deposition up to the frequencies in the kHz range. This new method could be used for...
Experimentální studium centrální a okrajové oblasti prstence plazmatu na tokamaku Compass
Štefániková, Estera ; Tichý, Milan (advisor) ; Hron, Martin (referee)
High-resolution Thomson scattering system on the COMPASS tokamak provides electron temperature and density profiles in the central and edge plasma region. The spatial resolution in the edge plasma region is optimized for edge transport barrier studies. Formation of characteristic edge profiles (pedestals) is observed during high-confinement mode, i.e. the core electron temperature and density are raised up by the value of pedestal height. Both the electron and density pedestals are well-fitted by a modified hyperbolic tangent (mtanh) function, a five parameter model giving important parameters such as pedestal height and width, necessary for further analysis of the physics behind the transport barrier formation. A fitting technique of the full radial profiles of electron temperature, density and pressure during H-mode is also described. Using the fitting, electron temperature and density on top of pedestal are statistically processed to find a possible threshold for various H-mode regimes.
New mass spectrometric methods for trace gas analysis of human breath.
Brůhová Michalčíková, Regina ; Španěl, Patrik (advisor) ; Polášek, Miroslav (referee) ; Tichý, Milan (referee)
This dissertation thesis summarizes results of experiments that have been carried out during my PhD studies related to the new mass spectrometric methods for trace gas analysis of human breath. The thesis is divided into the theoretical and experimental part. The chapter at the beginning of this dissertation summarizes the current research in the area of breath analysis. It is describing the common breath metabolites, benefits and challenges of the method for therapeutic monitoring and clinical diagnosis and current applications. The next chapter of the theoretical introduction describes the techniques suitable for this area of research, with a special emphasis on mass-spectrometric techniques (in particular the selected ion flow tube mass spectrometry, SIFT-MS, method that allows accurate quantification of trace gases and vapours in humid air/human breath). All these parts are elaborated via the scientific literature review. The following chapters are then directly related to my own research and describes the conducted experiment, including the results obtained. This experimental part "Results and Discussion" is divided to the individual subsections, which are conceived as the commentaries to the enclosed research papers published in peer reviewed journals. The first is the detailed step by step...
Study of Equilibrium Magnetic Configuration in Tokamak Type Devices
Havlíček, Josef ; Tichý, Milan (advisor) ; Kubeš, Pavel (referee) ; Van Oost, Guido (referee)
This thesis presents the magnetic fields of the COMPASS tokamak and work done during the COMPASS reinstallation in the Czech Republic. The geometry, vacuum magnetic fields and Power Supplies for the poloidal field coils circuits are described in the technical part of the thesis. The design of Power Supplies filters and improvements in the controller algorithm are also introduced. The MHD equilibrium reconstruction code EFIT++ and implementation of the induced currents model are described in the physical part of the thesis. The EFIT++ code was adapted for COMPASS. The utilization of the EFIT++ code for the COMPASS operation is shown. The global power balance in the non-stationary phases of the tokamak discharge is explained and examples are shown. The attached articles describe Power Supplies and tokamak feedback system developed for the COMPASS plasma control. Powered by TCPDF (www.tcpdf.org)
Development and application of methods for measurement of magnetic field on tokamaks
Kovařík, Karel ; Ďuran, Ivan (advisor) ; Mlynář, Jan (referee) ; Tichý, Milan (referee)
Title: Development and application of methods for measurement of magnetic field on tokamaks Author: Ing. Karel Kovařík Department: Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University in Prague Institute of Plasma Physics of the Czech Academy of Sciences, v. v. i. Supervisor: Ing. Ivan Duran, PhD. (Institute of Plasma Physics of the Czech Academy of Sciences, v. v. i.) Abstract: Thesis describes two parts of my work in frame of magnetic confined fusion research. First part describes irradiation testing of the Hall sensors based on InSb semiconductor. It evaluates radiation effects of fast and thermal neutrons on the Hall sensors sensitivity. Tests indicate low level of changes for fluence lower only by order of magnitude than expected in the whole lifetime of ITER tokamak. Second part describes measurement of turbulent plasma structures parameters in scrape--off layer of the COMPASS tokamak, particularly the parallel electric current flowing along them. Design of novel combined probe allowing measurement of not only electrostatic parameters but also the parallel electric current is presented. Evaluation of parallel electric current is discussed and compared with experiment. Statistical analysis of the plasma structures is presented. Empirical formulas of the...
Magnetic field Supported Discharge Based Plasma Sources
Havlíček, Josef ; Kudrna, Pavel (advisor) ; Tichý, Milan (referee)
Main aim of this work was measurement of a floating potential fluctuations in the cylindrical magnetron in classical configuration in neon. Two Langmuir probes were used for measurement of wave vector. The following values were measured: pressure p in range 1-7 Pa, magnetic induction B in range 10-40 mT, discharge current I in range 5-100 mA, discharge voltage U and floating potential Uf. Fluctuations were described by dependencies of power spectral density on frequency S(f) and by histograms S(k,f), where k is wave vector. Several discharge modes were observed in the magnetron. These are characterized by different values of discharge voltage, electric field in positive column, magnitude of the floating potential etc. The discharge conditions, where peaks were observed in spectra, were determined. Only one peak with frequency in range 4-16 kHz was mostly observed. Most of these peaks had zero wave vector in histogram S(k,f), i.e. the floating potential synchronously oscillated in the whole discharge area. For some discharge conditions histograms with non-zero wave vector for noise background were observed.
Měření potenciálu plazmatu pomocí ball-pen a Langmuirovy sondy
Peterka, Matěj ; Tichý, Milan (advisor) ; Komm, Michael (referee)
The ball-pen probe is a unique probe recently developed at the Institite of Plasma Physics in Prague. It has been designed for direct measurement of plasma potential at the CASTOR tokamak. It has also been succesfully tested on several other high-temperature plasma devices in Europe. The aims of the bachelor work are primarily experimental. A ball-pen probe has been constructed from available materials, which is suitable for measurement in the low-temperature plasma of a cylindrical magnetron. Although its parameters are much different from those in high-temperature plasma devices, the main principle of measurement with ball-pen probe has been proven to apply also in this brand-new conditions.

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See also: similar author names
5 TICHÝ, Martin
1 Tichý, M.
4 Tichý, Marek
1 Tichý, Marko
5 Tichý, Martin
1 Tichý, Matej
21 Tichý, Michal
3 Tichý, Mikuláš
1 Tichý, Miloslav
8 Tichý, Miloň
3 Tichý, Miloš
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