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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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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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Global Power Balance in Non-Stationary Discharge Phases in the COMPASS Tokamak
Havlíček, Josef ; Imríšek, Martin ; Kovařík, Karel ; Weinzettl, Vladimír
The global power balance between different input power and sink/loss channels is important for understanding of tokamak physics, particularly for various scaling laws. The power balance is measured easily during stationary discharge phases because the terms for both magnetic field energy and plasma thermal energy build-up can be neglected. However, many important events in tokamak plasmas occur during non-stationary phases of the discharge. This article describes, quantifies and discusses the terms of the global power balance, including time dependent parts, and exemplifies them on the typical ohmic discharge of the COMPASS tokamak.
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First measurements with U-probe on the COMPASS tokamak
Kovařík, Karel ; Ďuran, Ivan ; Stöckel, Jan ; Seidl, Jakub ; Šesták, David ; Brotánková, J. ; Spolaore, M. ; Martines, E. ; Vianello, N.
A complex electrostatic-magnetic probe diagnostics, baptized as ‘U-probe’, has been installed on COMPASS tokamak recently. Probe composes of two identical towers. Each tower houses 3 radially spaced sets of 3D coils, triple probe and rake probe – array of six Langmuir probes. The U-probe measures electric and magnetic properties of the filamentary structures in the edge plasma, particularly the floating potential profile and local magnetic field within the plasma filaments. Contribution presents first tests and results obtained.
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U-probe for the COMPASS Tokamak
Kovařík, Karel ; Ďuran, Ivan ; Stöckel, Jan ; Seidl, Jakub ; Šesták, David ; Brotánková, J. ; Spolaore, M. ; Martines, E. ; Vianello, N. ; Hidalgo, C. ; Pedrosa, M. A.
A complex electrostatic-magnetic probe diagnostics, baptized as 'U-probe', is being prepared for measurement of properties of the filamentary structures in the edge plasmas of COMPASS tokamak. Probe will be composed of two identical towers. Each tower will house 3 sets of 3D coils, balanced triple probe and six single Langmuir probes each. The design of the probe is based on that of U-probe used on reversed field pinch RFX-mod and our combined electromagnetic probe at TJ-II stellarator. This new COMPASS diagnostic will measure vorticity and longitudial electric current of the plasma filaments. Analysis of the properties and, particularly, the correlation between filament vorticity and its current is expected to shed light into physics of filamentary structures in the tokamak plasma edge. The simulation of the probe surface temperature evolution as a function of expected incident heat loads within the COMPASS edge plasmas is presented.
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Ozařovací testy Hallových senzorů
Kovařík, Karel ; Ďuran, Ivan ; Oszwaldowski, M. ; Viererbl, L.
A principally new diagnostic method has to be developed to complement the magnetic measurements in true steady state regime of operation of future fusion reactors. One of the options is the use of diagnostics based on Hall sensors that are well established in experimental physics and industry, although it is rarely implemented in the fusion plasma physics due to short pulse operation of majority of present day tokamaks. There are two main issues associated with the use of Hall sensors in harsh environment of future fusion reactors i.e. low survival temperature of presently available commercial transducers and questionable stability of these mostly semiconductor sensors under neutron irradiation. Hall sensors based on InSb thin film layers are presently being evaluated as one of the perspective options for ITER ex-vessel steady state magnetic sensors. Here, the compatibility with vacuum vessel baking temperature of 220 oC and with the peak life time neutron fluence of 1018 n/
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