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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...
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RE beam generation in MGI disruptions on COMPASS.
Ficker, Ondřej ; Mlynář, Jan ; Macúšová, Eva ; Vlainić, M. ; Weinzettl, Vladimír ; Urban, Jakub ; Čeřovský, Jaroslav ; Farník, Michal ; Markovič, Tomáš ; Papřok, Richard ; Vondráček, Petr ; Imríšek, Martin ; Tomeš, Matěj ; Havlíček, Josef ; Varju, Jozef ; Varavin, Mykyta ; Bogár, Ondrej ; Havránek, Aleš ; Gospodarczyk, M. ; Rabinski, M. ; Jakubowski, M. ; Malinovski, K. ; Zebrowski, J. ; Plyusnin, V. ; Papp, G. ; Pánek, Radomír ; Hron, Martin
In the experiments with the massive gas injection (MGI) triggered disruptions in the COMPASS tokamak, post-disruptive runaway electron (RE) beams are generated occasionally. In this contribution, a relatively large set of discharges from the recent years is analysed in order to improve our understanding of the processes behind the beam generation. It seems that despite the low toroidal field applied in the discharges (typically 1.15 T) the magnetic perturbations may be small enough to allow the acceleration and confinement of the electrons. The influence of the different components and different sections of the frequency spectrum of the magnetic perturbations on the beam generation and RE beam current is examined. Fast visible camera images are also analysed. The relevance of COMPASS runaway electron experiments for large machines is discussed. Moreover, the potential of less common diagnostic tools (Cherenkov detector, vertical ECE, ...) to clarify the role of the pre-disruption fast electron population and the influence of prompt runaway electron losses in the current quench is discussed using the recent test measurements.
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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...
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Thomson Scattering Diagnostic on COMPASS Tokamak
Aftanas, Milan ; Stöckel, Jan (advisor) ; Mlynář, Jan (referee) ; Wild, Jan (referee)
Thorough study of plasma behaviour in magnetically confined fusion devices is of great importance in recent research. Diagnostics capable to reliably provide important parameters of the hot plasma are key tool in the effort to control fusion energy on Earth. Thomson Scattering diagnostic has a credit of being a complex design diagnostic with reliable measurement of electron temperature and density profiles. The main subjects of this thesis are design of the Thomson Scattering system for the COMPASS tokamak, analysis of output data errors and exploitation of the data to study plasma behaviour. Besides this work, the author has been involved in the design of Thomson Scattering systems for the ITER tokamak and this design is presented here as well. Powered by TCPDF (www.tcpdf.org)
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Chapters of the Nuclear Fusion for Secondary Schools
Řehák, Česlav ; Mlynář, Jan (advisor) ; Koupilová, Zdeňka (referee)
Title: Chapters from nuclear fusion for high school education Author: Česlav Řehák Department: Didactics of physics Supervisor: RNDr. Jan Mlynář, Ph.D., Faculty of nuclear physics and engineering, ČVUT Abstract: Text of this thesis is intended for anyone interested in nuclear fusion, although it is especially aimed for education of physics in high schools. The thesis sums up the basic principles of fusion reactions in space and explains it's importance for life on Earth. Additionally, it points out some of the most crucial problems of present world energetics and introduces controlled thermonuclear fusion as a possible solution. The thesis clarifies some of the most important aspects of controlled fusion research, especially the branch of magnetic confinement reactors, and provides the most significant advantages and disadvantages of this potential power source. It also offers variety of illustrative pictures. Keywords: Nuclear fusion, energetics, magnetic confinement, tokamak
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Gap – gep – gap?
Obdržálek, J. ; Bílková, Petra ; Mlynář, Jan
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
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Unfolding of energies of fusion products measured by the activation probe at JET
Ficker, Ondřej ; Mlynář, Jan ; Bonheure, G. ; Murari, A. ; Popovichev, S.
Providing a detection method for diagnostic of charged fusion products in tokamaks presents a major challenge, while its absolute calibration with a sufficient accuracy and its capability to withstand harsh fusion reactor environment will be required. A novel type of detector that meets most of these requirements, based on an activation probe, was tested in JET and other European facilities. This probe proved to be extremely robust due to its simple construction. It is equipped with samples of well defined isotopic abundance. The amounts of activated nuclei due to the reactions in these materials could be measured via ultra-low-level gamma spectroscopy. The feasibility of the proton spectrum reconstruction from measured activities is examined in this contribution with the help of the algorithm based on the Tikhonov regularisation constrained by minimum Fisher information. The reliability of the method was previously illustrated using synthetic proton data.
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