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Characterization and focusing of capillary-discharge XUV-laser beam for purposes of thin-film deposition
Pira, Peter ; Wild, Jan (advisor) ; Čuba, Václav (referee) ; Tichý, Milan (referee)
Title: Characterization and focusing of capillary-discharge XUV-laser beam for purposes of thin-film deposition Author: Peter Pira Department: Department of Surface and Plasma Science Supervisor: doc. RNDr. Jan Wild, CSc., Department of Surface and Plasma Science Abstract: The paper deals with the first results of the interaction of a desk-top high repetition rate XUV laser (wavelength of 46.9 nm) radiation with materials suitable for optoelectronics, in particular the ionic crystals CsI, LiF, etc. Using surface physics methods (AFM, DIC Normanski microscopy) pulse laser imprints were investigated. Based on the results obtained, general information on the nature of ablation and desorption was obtained, which were compared with the results of the XUV-ABLATOR modified code modeling. Plasma arising from ablation was examined by a modified Langmuir probe system. The main result is the pulse laser deposition of thin films of Bi and CsI. Keywords: ablation, Pulsed Laser Deposition, XUV laser
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Probe diagnostics of the pulse-generated plasma
Turek, Zdeněk ; Tichý, Milan (advisor) ; Kaňka, Adolf (referee)
The subject of the bachelor thesis is the plasma diagnostics in the planar magnetron and in the hollow cathode system operating in the pulse mode, when the plasma is generated by DC pulses. The diagnostics method used will be the Langmuir probe. The aim of the thesis is the construction of the computer-controlled electronic measuring system and its assessment when measuring the parameters of argon discharge plasma in both systems with time resolution i.e. depending on time during one pulse period.
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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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Spacecraft observations of waves in low-latitude magnetospheric plasma
Sochorová, Zuzana ; Santolík, Ondřej (advisor) ; Chum, Jaroslav (referee) ; Tichý, Milan (referee)
Title: Spacecraft observations of waves in low-latitude magnetospheric plasma Author: Zuzana Sochorová Department: Department of Surface and Plasma Science Supervisor: prof. Ondřej Santolík, Department of Surface and Plasma Science, Institute of Atmospheric Physics AS CR Abstract: The present doctoral thesis is based on the analysis of the electromagne- tic equatorial noise (EN) emissions. These waves propagate in the vicinity of the geomagnetic equator at frequencies between the local proton cyclotron frequency and the lower hybrid frequency. We used data obtained by the 4 Cluster spacecraft during the period from January 2001 to December 2010. The analysis is based on the data from the STAFF-SA instrument. We have developed 3 selection criteria for the visual identification and we have compiled a database of more than 2000 events. We demonstrate than EN occurs in almost entire analyzed range of the McIlwain's parameter from about L ∼ 1 to L ∼ 10. EN mostly occurs between L = 3 and L = 5.5. Analysis of occurrence rates as a function of magnetic local time shows strong variations outside of the plasmasphere (with an increase in the afternoon sector), while the occurrence rate inside the plasmasphere is almost independent. We have also analyzed the inner structure of EN. We use data from the WBD instrument...
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Ion processes in gases for the trace analysis of volatile compounds in air
Spesyvyi, Anatolii ; Španěl, Patrik (advisor) ; Matejčík, Štefan (referee) ; Tichý, Milan (referee)
This thesis describes development of the new selected ion flow-drift tube mass spectrometry technique, SIFDT-MS, for online quantification of volatile organic compounds, VOCs, based on gas phase ion-molecule reactions. SIFDT-MS represents a new generation of the successfully used selected ion flow tube, SIFT- MS, analytical method. The essential extension of SIFDT-MS is the uniform electric field E applied across the flow tube reactor, thus converting it to the flow-drift tube where the ion processes can be governed by strength of field E. Newly introduces Hadamard modulation of the gate lens before the flow-drift tube enables direct ion residence, and correspondently ion-molecule reaction, time measurement that is necessary for the precise concentration calculations under variable conditions. The detailed experimental study of these processes results was carried out to form a basis of the analytical method. In order to overcome a well-known issue of SIFT-MS, when mass spectral peaks of isobaric ions overlap, the pseudoinverse matrix multiplication for isobaric mixtures was demonstrated. Finally two data mining approaches were successfully tested on the data of the fragmentation signals of seven monoterpene isomers obtained in SIFT-MS.
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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)
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Experimental study of the use of probe methods for diagnostic of low-temperature magnetized plasma
Zanáška, Michal ; Tichý, Milan (advisor) ; Adámek, Jiří (referee)
The ball-pen probe is a relatively new diagnostic method, that has been designed for direct measurement of plasma potential in magnetized plasmas. Nowadays, it is routinely used at several high-temperature plasma devices in Europe and it has been tested also in conditions of low-temperature plasma, which are substantially different from that of high-temperature plasma. The measurements performed so far showed, that ball-pen probe could be used also in low-temperature plasma. However, more measurements were needed to prove the applicability of ball-pen probe. Therefore, the main aim of this work is to compare the method of ball-pen probe with simultaneous measurements using Langmuir and emissive probe. Measurements were performed in DC discharge of cylindrical magnetron at various discharge conditions and radial positions of probes. Powered by TCPDF (www.tcpdf.org)
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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.
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Experimental and theoretical study of utilization of probe methods for plasma diagnostics
Peterka, Matěj ; Tichý, Milan (advisor) ; Horáček, Jan (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. Nowadays, it is used routinely at several tokamaks in Europe, and the first tests in low-temperature plasma have also already been performed. The aims of the thesis are primarily experimental. A ball-pen probe has been constructed from available materials, which is suitable for systematic measurements of radial profiles in the low-temperature plasma of a cylindrical magnetron. By means of comparison to other diagnostics, it was proved that ball- pen probe is able to directly measure plasma potential in a certain range of plasma parameters even though its current-voltage characteristic is not symmetric, which is in contradiction with the simplified theory for ball-pen probe. Powered by TCPDF (www.tcpdf.org)
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