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Parallel Heat Flux Decay Length Study in the COMPASS Tokamak Using MWIR and LWIR Cameras
Vondráček, Petr ; Horáček, Jan ; Pánek, Radomír ; Gauthier, E.
A comprehensive study of a parallel heat flux in a tokamak scrape-off layer (SOL) has been performed in the COMPASS tokamak recently. Specially shaped high field side (HFS) limiter was used to estimate a heat flux radial decay length for small limiter radial misalignment. Long wavelength IR microbolometer and medium wavelength IR InSb camera were used for this purpose. This paper compares results obtained by the means of both cameras and demonstrates observation of very narrow heat flux decay length close to the last closed flux surface (LCFS) independantly on used camera.
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New Detection System for Fast Density Measurements Using the Lithium Beam on the COMPASS Tokamak
Háček, Pavel ; Berta, M. ; Stöckel, Jan ; Weinzettl, Vladimír ; Anda, G. ; Bencze, A. ; Zoletnik, S.
The lithium beam diagnostic at COMPASS is designed for measurements of the edge plasma density profile and fluctuations and edge plasma current fluctuations. The principle of the diagnostic is detection of light coming from collisionally excited Li atoms — beam emission spectroscopy (BES) - and a direct detection of the ionized part of the beam (atomic beam probe — ABP). For slow density measurements a charged coupled device (CCD) camera has been installed and is already working. For fast twodimensional density profile and density fluctuation measurements an array of avalanche photodiode detectors (APDs) will be used. The two-dimensional resolution of the measurement will be possible using fast poloidal deflection and chopping of the beam. Apart from routine density profile measurement, the diagnostic will be capable of investigating the turbulent structures in the edge plasma by cross-correlating the signals coming from poloidally deflected virtual beams.
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Infrared Thermography on the COMPASS Tokamak
Vondráček, Petr ; Horáček, Jan ; Cahyna, Pavel ; Pánek, Radomír ; Uličný, J.
This contribution describes a new slow infrared camera obtained by the COMPASS tokamak at IPP Prague. We focus on the camera limitations affecting the experimental data (temporal and spatial smoothing, time shift). Data time deconvolution used to correct the effect of the long response time of the camera detector is described. The second part of the contribution is devoted to the physic basis for the design of a new fast IR camera system planned for installation in COMPASS during the next year.
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Diagnostic Lithium Beam System for COMPASS Tokamak
Háček, P. ; Weinzettl, Vladimír ; Stöckel, Jan ; Anda, G. ; Veres, G. ; Zoletnik, S. ; Berta, M.
The COMPASS tokamak has been re-installed in IPP Prague after its transport from Culham in UK. A Diagnostic Lithium Beam system is being developed for COMPASS tokamak. Its main goal is to provide edge density (Beam Emission Spectroscopy) and edge plasma current (Atomic Beam Probe) measurements to address the scientific programme focused on H-mode and pedestal physics. It features several newly designed and developed parts, including improved emitter and neutralizer. Atomic Beam Probe is an innovatory diagnostic for measurement of poloidal magnetic field and plasma current fluctuations in the plasma edge. Currently, the system is connected to tokamak (August 2011) and first experiments with plasma were performed. The system still undergoes vacuum, neutralization and high voltage testing. This article reviews the concept and current state of the Lithium Beam diagnostic for COMPASS and provides its first test results.
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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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Atomic Beam Probe Diagnostic for COMPASS Tokamak
Háček, Pavel ; Weinzettl, Vladimír ; Stöckel, Jan ; Anda, G. ; Veres, G. ; Zoletnik, S. ; Berta, M.
The COMPASS tokamak has been re-installed in IPP Prague after its transport from Culham in UK. New diagnostic tools are under development to address the scientific program focused on H-mode and pedestal physics. Atomic Beam Probe (ABP) is an innovatory diagnostic for measurement of poloidal magnetic field and plasma current fluctuations in the plasma edge. It is planned to be an extension of the beam emission spectroscopy system by collecting the lithium ions stemming from beam ionization. In the first approximation, ionization is proportional to the local plasma density. The poloidal magnetic field moves the ions toroidally. Therefore, the two-dimensional poloidal-toroidal measurement of the ion current in the exit port reveals information on both the density and magnetic field profiles, thereby also on the edge current profile. This article reviews the concept of the ABP diagnostic and the status of its installation on the COMPASS tokamak.
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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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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.
Tokamak COMPASS, původně z UKAEA z Culham laboratory ve Velké Británii, bude reinstalován v Ústavu fyziky plazmatu v Praze. Vědecký program je zaměřen především na výzkum oblasti okrajového plazmatu s velkými gradienty elektronové teploty a hustoty, zvané pedestal. Na tokamaku bude provedeno mnoho inovací a postavena nová diagnostika. Klíčovou diagnostikou je pak nekoherentní Thomsonův rozptyl pro měření elektronové teploty a hustoty s vysokým prostorovým rozlišením. Zde je diskutována možnost použití Nd:YAG laseru v kombinaci s detekčním systémem na bázi lavinových diod.
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Nový systém s vysokým rozlišením pro měření Thomsonova rozptylu na tokamaku COMPASS
Brotánková, Jana ; Bělský, Petr ; Weinzettl, Vladimír ; Böhm, Petr ; Barth, R. ; van der Meiden, H.
Thomsonův rozptyl je diagnostická technika umožňující měřit elektronovou teplotu a hustotu. Pro systém Thomsonova rozptylu na tokamaku COMPASS bylo zváženo několik možných variant, pro které byly spočteny relevantní parametry jak pro středové, tak pro okrajové plazma. Aby bylo možno realizovat měření očekávaných hodnot elektronové hustoty a teploty, byly vybrány dvě nejvhodnější varianty: (i) Nd-YAG laser na druhé harmonické frekvenci v kombinaci s Littrowovým spectrometrem a ICCD kamerou (pro středový i krajový systém) a (ii) Nd-YAG laser na první harmonické frekvenci v kombinaci s Littrowovým spectrometrem s CMOS kamerou (pro středový systém) a spektrálními filtry s lavinovými diodami (pro krajový systém).
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