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Forward and Backward Modelling of Spectroscopic Diagnostics in Fusion Plasmas
Tomeš, Matěj ; Seidl, Jakub (advisor) ; De Bock, Maarten (referee) ; Den Hartog, Daniel J. (referee)
Title: Forward and Backward Modelling of Spectroscopic Diagnostics in Fusion Plasmas Author: Matěj Tomeš Department: Department of Surface and Plasma Science Supervisor: Mgr. Jakub Seidl, Ph.D., Institute of Plasma Physics of the Czech Academy of Sciences Abstract: The thesis primarily focuses on developing forward and backward models for fusion diagnostics. It encompasses the development and application of these models for Thomson scattering, the inference of neon concentrations in JET's divertor and for synchrotron radiation. In the first chapter, the forward model of Thomson scattering designed for Cherab is detailed. This includes the development of a laser module intended for a wide range of applications, primarily to facilitate Thomson scattering simulations. An application example is provided by a comprehensive model of the Thomson scattering diagnostic used at the COMPASS tokamak. The model of the diagnostic is combined with experimentally obtained electron profiles to assess its performance. The second half of the chapter focuses on the development of a backward model for Bayesian inference of temperature profiles from measured Thomson scattering data. The effectiveness of this model is compared to the conventional approach based on least square error optimization, revealing clear advantages of...
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Utilization and Suppression of Birefringence Phenomena in Optical Fiber Sensory Applications
Motúz, Rastislav ; Hudcová, Lucie (referee) ; Vlček, Čestmír (referee) ; Drexler, Petr (advisor)
The thesis deals with integral and distributed optical fiber sensors of electric current. In the area of integral sensors the analysis is performed by Jones matrix calculus and the simultaneous influence of induced circular and undesired linear birefringence using an ortho-conjugation retroreflector. Furthermore, the proposed conjugation loop variant using half-wave phase retarders is analyzed. The theoretical conclusions are confirmed by simulation and experimental measurement. In the field of distributed fiber optic sensors, analysis and simulation for the detection of plasma currents in thermonuclear fusion reactors, based on the POTDR technique, is performed. An improvement procedure is proposed for circular-shaped vacuum vessel reactors. Plasma current detection procedure in divertor-type reactors have been newly designed and simulated to investigate the effect of the OTDR detector noise on plasma current detection accuracy.
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Thermonuclear fusion for power generation
Osolsobě, Jiří ; Elbl, Patrik (referee) ; Sitek, Tomáš (advisor)
Controlled thermonuclear fusion opens up the possibility of using similar principles that take place in stars to produce energy on planet Earth. A fusion power plant would represent a stable, safe, emission-free and, for the foreseeable future, inexhaustible source of energy. Currently, the most researched fusion device is a tokamak using magnetic confinement of plasma, which is likely to become the reactor of the first fusion power plant. The international ITER tokamak will be a breakthrough project for the further development of controlled thermonuclear fusion, with the main objective of testing a number of key technologies and the suitability of the tokamak as a fusion power plant reactor. According to the European Union's plans, construction of the first EU-DEMO fusion power plant should start around 2040. This bachelor thesis provides a comprehensive overview of the origins, current status and future prospects of thermonuclear fusion and its energy applications.
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Protective circuits of PF converters
Hauptmann, R. ; Kokeš, Petr
Description and results of numerical simulations of circuits, which provide damage protection of the main power supply circuit for tokamak PF (Poloidal Field) coils under emergency conditions, is presented. In case of normal operation the protection circuits do not affect operation of the power supply circuitry. The protection circuits represent a separate system which is functionally independent of circuits and control of power converters. Functinality of this system is designed as a safety circuit - a fault of the protection system always causes safety shut-down of the device.
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Protective circuits of TF converters
Hauptmann, R. ; Kokeš, Petr
Description and results of numerical simulations of circuits, which provide damage protection of the main power supply circuit for tokamak TF (Toroidal Field) coils under emergency conditions, is presented. In case of normal operation the protection circuits do not affect operation of the power supply circuitry. The protection circuits represent a separate system which is functionally independent of circuits and control of power converters. Functinality of this system is designed as a safety circuit - a fault of the protection system always causes safety shut-down of the device.
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Stability Analysis of Power Transfer in PF Supply System of Compass-U Tokamak.
Kokeš, Petr ; Hauptmann, R.
Power transfer stability in supply circuits of PF (Poloidal Field) coils has been analysed. Proper energizing of these coils is necessary for COMPASS-U tokamak experiments. The analysis main method is linearization of a non-linear system in a steady-state working point. The steady state-points have been specified by the Institute of Plasma Physics ASCR so that the whole operating area of the tokamak would be involved. At first, a simplified numerical model has been set up and analysed, then the analysis of a complex model of the PF supply system has been carried out in several versions according to the requirements of the contractor.
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Diffusion of Particles from Tokamak by Stochastization of Magnetic Field Lines
Cahyna, Pavel ; Krlín, Ladislav (advisor) ; Rohlena, Karel (referee) ; Suttrop, Wolfgang (referee)
The thesis summarizes the current state of research of thermonuclear fusion with magnetic confinement and decribes the possible role of stochastization of magnetic field lines and magnetic perturbations in solving some of the problems that are encountered on the road to the exploitation of fusion. It presents a theoretical introduction to deterministic chaos and explains the connection of this theory to magnetic perturbations in tokamak. The results are presented mainly in the form of publications in journals and conference proceedings. Among them are: the comparison of chaotic diffusion of particles and field lines, where significant differences were found; the application of chaotic diffusion of particles to the problem of runaway electrons originating in disruptions, where our simulations contributed to explaining the experimental results from the JET tokamak; the calculation of spectra of perturbations for the COMPASS tokamak, done as a preparation for the upcoming experiments; and modelling of screening of perturbations by plasma, where the observations of divertor footprints show as a promising method to detect the screening.
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Studium turbulence plazmatu tokamaku pomocí reciprokých sond
Ondáč, Peter ; Horáček, Jan (advisor) ; Komm, Michael (referee)
This thesis deals with the study of turbulence in tokamak plasma and im- provement of an computer model ESEL. The first chapter deals with the theory related to the study of turbulence in the plasma. For the study of these tur- bulences the results of the probe measurements on the ASDEX Upgrade and COMPASS tokamak and model results from a computer model of the turbulent ESEL are used. The second chapter describes the used probes and the third chapter describes the model ESEL. Contribution of the work is mainly in the fourth and fifth chapter, which summarize the results of the comparisons be- tween the experimental data and model ESEL. The sixth chapter summarizes the most important conclusions from these comparisons. Some agreements and discrepancies were shown. One of the main results of the thesis is the impor- tance of one extra term in one governing equation of the ESEL, which means its improvement. However at present the ESEL is still not able to fully describe the tokamak plasma boundary. 1
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Design and implementation of the plasma control system for the COMPASS tokamak
Janky, Filip ; Horáček, Jan (advisor) ; Kudrna, Pavel (referee) ; Svoboda, Vojtěch (referee)
Design and implementation of the plasma control system Mgr. Filip Janky The COMPASS tokamak was recommissioned in 2007 and it needed new digital controllers for its experimental research. This thesis presents the design and imple- mentation of control of main plasma parameters such as plasma current, plasma position, plasma shape and electron density. Improved plasma current control with resetting set points suppresses overshooting and thus increases the length of the flat top phase. A method for estimating the plasma position, gain tuning for the controller and decreasing latencies and delays to obtain robust position control are presented. Lower delays improve plasma stability and decrease the frequency of disruptions. The plasma shape controller is a feedforward controller with a method to suppress oscillations which are coming from mutual inductance between power supplies controlling plasma horizontal position, plasma shape and plasma current, which all use the same coil. Averaged electron density is corrected in real-time according to the interferometer line of sight and a non-linearity of measurement. Controllers and their improvements described here, played a major role in achiev- ing H-mode scenario and fulfilling the experimental program. Keywords: tokamak, plasma current control, plasma position...
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