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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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Data Acquisition System and Data Processing for the New Thomson Scattering System on the COMPASS Tokamak
Aftanas, Milan ; Bílková, Petra ; Böhm, Petr ; Weinzettl, Vladimír ; Stöckel, Jan ; Hron, Martin ; Pánek, Radomír ; Scannell, R. ; Walsh, M.
The Thomson scattering (TS) will be one of crucial plasma diagnostics of the COMPASS tokamak. This newly build-up multi-point system consists of two Nd:YAG lasers (1.6J at 1064nm, 30Hz each) and cascade filter polychromators with avalanche photodiodes. It will enable measurements of both the electron temperature Te (20eV − 5000eV ) and density ne (1019 − 1020m−3) profiles with spatial resolution up to 3mm in the vertical direction in 56 spatial points. The uniquely designed complex data acquisition system based on fast analog digital convertors (1GS/s) reflects the need to retrieve/digitize the signal originated from scattering process of the laser pulse lasting less than 10ns. This paper presents a detailed review of the architecture of the control and the data acquisition (DAQ) system and its features. LabViewr will be used as a main layer for the TS data acquisition. Routines specifically written for controlling the DAQ of TS on COMPASS are presented.
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Measurement of the Laser Beam Position and Width for the Thomson Scattering Diagnostics on Tokamak COMPASS
Aftanas, Milan ; Bílková, Petra ; Böhm, Petr ; Weinzettl, Vladimír ; Stöckel, Jan ; Hron, Martin ; Pánek, Radomír
COMPASS tokamak is equipped with new key diagnostic—Thomson scattering system. This unique multi-point system has been designed with the main aim to investigate electron density and temperature profiles on the COMPASS tokamak (R = 0.56 m, a = 0.18 m, BT max = 2.1 T). The spatial resolution is optimized namely for the pedestal studies (radial spatial resolution a/100). This contribution describes particular steps of optical alignment of the important part of the Thomson scattering system, Nd:YAG lasers (1.6 J at 1064 nm, 30 Hz). Laser beam width has to be precisely measured and laser beam position has to be precisely set before the measurement and checked for all laser shots to be able of decrypting the information about the plasma density and also to improve precision of the measurement. New tool for automatic measurement of the laser beam misalignment is introduced.
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Navrh filtru pro detekci Thomsonovym rozptylem na tokamaku COMPASS
Aftanas, Milan ; Scannell, R. ; Bílková, Petra ; Böhm, Petr ; Weinzettl, Vladimír ; Walsh, M.
Reinstalled tokamak COMPASS, originally from Culham Science Centre, is now operating at the Institute of Plasma Physics, Prague and many new optical diagnostics are being developed [Sestak et al, 2009]. For measurement of electron temperature and density profiles, high resolution incoherent Thomson scattering spectroscopy based on Nd:YAG laser and avalanche photodiodes is under development now. The paper outlines part of the design of this diagnostic - proper choice of spectral filters. The design of filters is shown and its evaluation taking into account different angle of scattered light is introduced. Error bars of the electron temperature, density and pressure are determined with respect to assumed electron temperature and density profiles and to required high spatial resolution at the pedestal region.
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Odhad zareni z plazmatu v systemu Thomsonova rozptylu projektovaneho pro tokamak COMPASS
Aftanas, Milan ; Böhm, Petr ; Weinzettl, Vladimír ; Stöckel, Jan
The COMPASS tokamak, originally from Culham laboratory, UKAEA, has been reinstalled at at Institute of Plasma Physics, Prague. Many innovations will be done and new diagnostics have to be constructed. Electron temperature Te and density ne as as key parameters of fusion plasma will be measured directly by the newly designed high spatial resolution incoherent Thomson scattering (TS) system. Several construction options of TS are considered. In this paper these options are discussed from a point of view of data analysis and estimation of background radiation.
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Využití lavinových fotodiod pro diagnostiku Thomsonova rozptylu na tokamacích
Aftanas, Milan ; Bělský, Petr ; Böhm, Petr ; Weinzettl, Vladimír ; Brotánková, Jana ; Barth, R. ; van der Meiden, H.
The COMPASS tokamak, originally from UKAEA, Culham laboratory, U.K., will be reinstalled at Institute of Plasma Physics, Prague. The scientific programme is focused mainly on the investigation of the edge plasma region with high temperature and density gradients called pedestal. Many innovations will be done and new diagnostics have to be constructed. One of the key diagnostics is an incoherent Thomson scattering for measurements of electron temperature Te and density ne with a high spatial resolution. In this paper a possibility of using a Nd:YAG laser in combination with a detection system based on Avalanche Photodiodes is discussed.
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Nová diagnostika pomocí Thomsonova rozptylu pro tokamak COMPASS
Aftanas, Milan ; Bělský, Petr ; Böhm, Petr ; Weinzettl, Vladimír ; Brotánková, Jana ; Barth, R. ; van der Meiden, H.
The COMPASS tokamak, originally from UKAEA, Culham laboratory, U.K., will be reinstalled at Institute of Plasma Physics, Prague. The scientific programme is focused mainly on the investigation of the edge plasma region with high temperature and density gradients called pedestal. Many innovations will be done and new diagnostics have to be constructed. One of the key diagnostics is an incoherent Thomson scattering for measurements of electron temperature Te and density ne with a high spatial resolution. Several construction options are considered. In this paper a possibility of using a Nd:YAG laser in combination with a detection system based on Avalanche Photodiodes is discussed.
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