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The Absolute Sensitivity Measurements of Spectra in Near IR Range at the COMPASS Tokamak
Naydenkova, Diana; Stöckel, Jan; Weinzettl, Vladimír
2014 - English
The new impurity survey spectrometer HR 2000+ is used for registration of the most intense spectral lines in the 654–1085 nm near IR range with spectral resolution 0.23 nm and temporal resolution from 4 ms to discharge duration at the COMPASS tokamak. The procedure of the absolute calibration of the spectrometer is described and technical issues and experimental limitations connected with its operation are discussed here. The measured spectra are interpreted and results are discussed.
Keywords:
tokamak; COMPASS; spectrometer HR 2000+
Fulltext is available at external website.
The Absolute Sensitivity Measurements of Spectra in Near IR Range at the COMPASS Tokamak
The new impurity survey spectrometer HR 2000+ is used for registration of the most intense spectral lines in the 654–1085 nm near IR range with spectral resolution 0.23 nm and temporal resolution ...
Infrared Thermography on the COMPASS Tokamak
Vondráček, Petr; Horáček, Jan; Cahyna, Pavel; Pánek, Radomír; Uličný, J.
2013 - English
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.
Keywords:
Plasma diagnostics; infrared camera; tokamak
Fulltext is available at external website.
Infrared Thermography on the COMPASS Tokamak
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 ...
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.
2013 - English
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.
Keywords:
Diagnostic lithium beam; Plasma diagnostics; tokamak
Fulltext is available at external website.
New Detection System for Fast Density Measurements Using the Lithium Beam on the COMPASS Tokamak
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 ...
Planar acoustic metamaterials with the active control of acoustic impedance using a piezoelectric composite actuator
Nováková, Kateřina; Mokrý, P.; Václavík, J.; Marton, P.; Cernik, M.; Psota, Pavel; Doleček, Roman; Lédl, Vít
2013 - English
In the Paper, there are presented methods for a precise active control of the acoustic impedance of large planar structures, e.g glass plates or shells, by means of distributed flexible piezoelectric composite actuators which are connected to passive or active electronic shunt circuits. Design of tunable acoustic metamaterials is realized using Finite Element Method simulations and their acoustic properties are evaluated using acoustic transmission loss measurements. Static and dynamic displacements of the metamaterials produced by electric voltage are measured using Digital Holographic Interferometry. We believe that deep understanding of presented systems should result in future applications that improve the quality of everyday life.
Keywords:
Planar acoustic metamaterials; Active control of acoustic impedance; Piezoelectric composite actuator
Available at various institutes of the ASCR
Planar acoustic metamaterials with the active control of acoustic impedance using a piezoelectric composite actuator
In the Paper, there are presented methods for a precise active control of the acoustic impedance of large planar structures, e.g glass plates or shells, by means of distributed flexible piezoelectric ...
Design and Preliminary Results of the COMPASS Power Supplies Filters
Havlíček, Josef; Zajac, Jaromír
2013 - English
The COMPASS tokamak uses rectifying thyristor converters as Power Supplies for the major slow coils circuits. 24-pulse thyristor converter is used for Toroidal Field circuit and 12-pulse converters are used for Magnetizing, Equilibrium and Shaping Field circuits. A noise generated by the switching of the converters negatively influences diagnostics measuring the plasma. The article describes design phase and some preliminary results of the filters for the Power Supplies
Keywords:
COMPASS tokamak; magnetic field; plasma
Fulltext is available at external website.
Design and Preliminary Results of the COMPASS Power Supplies Filters
The COMPASS tokamak uses rectifying thyristor converters as Power Supplies for the major slow coils circuits. 24-pulse thyristor converter is used for Toroidal Field circuit and 12-pulse converters ...
Absolute Sensitivity Calibration of Visible Spectroscopic Diagnostic and Temporal Evolution of First Window Transmittance at the COMPASS Tokamak
Naydenkova, Diana; Weinzettl, Vladimír; Stöckel, Jan; Háček, Pavel; Imríšek, Martin
2013 - English
An absolute calibration of spectroscopic systems is required to measure many important plasma parameters in tokamak discharges like impurity inflow, recycling and the effective ion charge. The procedure of the absolute calibration is described and technical issues and experimental limitations connected with the tokamak operation are discussed here. Namely, an influence of the first window transmittance and its evolution over experimental campaigns on the validity of the absolute calibration is investigated
Keywords:
COMPASS; tokamak; Visible Spectroscopic Diagnostic; Absolute Sensitivity; Calibration
Fulltext is available at external website.
Absolute Sensitivity Calibration of Visible Spectroscopic Diagnostic and Temporal Evolution of First Window Transmittance at the COMPASS Tokamak
An absolute calibration of spectroscopic systems is required to measure many important plasma parameters in tokamak discharges like impurity inflow, recycling and the effective ion charge. The ...
Observation of Sawtooth Oscillations in the COMPASS Tokamak
Imríšek, Martin; Havlíček, Josef; Weinzettl, Vladimír; Mlynář, Jan
2013 - English
The sawtooth instability in tokamak plasmas results in periodic relaxations of the core plasma density and temperature. The physics of sawtooth is still not fully understood. It is predicted that fusion-born alpha particles will lead to long sawteeth. However, longer sawteeth can seed other instabilities which cause further degradation of plasma confinement. This paper provides brief introduction into sawtooth physics and observations of sawtooth instability in COMPASS. Furthermore, evidence of triggering transition to high confinement regime by sawtooth crash is presented
Keywords:
Sawtooth; tokamak; soft-x ray; COMPASS
Fulltext is available at external website.
Observation of Sawtooth Oscillations in the COMPASS Tokamak
The sawtooth instability in tokamak plasmas results in periodic relaxations of the core plasma density and temperature. The physics of sawtooth is still not fully understood. It is predicted that ...
Observation and Prediction of Runaway Electrons in the COMPASS Tokamak
Papřok, R.; Krlín, Ladislav; Stöckel, Jan
2013 - English
In this paper we present new measurements of HXR radiation from the COMPASS tokamak by the use of scintillation detector, 21-pinhole CdTe semiconductor detector. This radiation is caused by the presence of highly energetic runaway electrons and in the case of Neutral Beam Injection by fusion products. We also present direct runaway electrons measurements by Cherenkov detector. We present a theoretical prediction of runaway production based on theoretical formula and experimental data from Thomson scattering and compare it with a simpler experimental method based on peak counting.
Keywords:
tokamak; COMPASS
Fulltext is available at external website.
Observation and Prediction of Runaway Electrons in the COMPASS Tokamak
In this paper we present new measurements of HXR radiation from the COMPASS tokamak by the use of scintillation detector, 21-pinhole CdTe semiconductor detector. This radiation is caused by the ...
Possibilities of welding observation with regard of sielding gas
Rohan, P.; Vojtíšek, Petr
2013 - English
MAG welding is characterized by very rapid processes in extreme condition of electric arc. To describe welding is necessary to use sufficiently quick equipment. Especially in the transition region between dip and spray transfer the processes develop quickly. Characterization of transition area in active three component shielding gas was carried out visually by hi speed camera equipment and electrically by quick response electronic measurement system.
Keywords:
Welding; direct observation; welding gas
Available at various institutes of the ASCR
Possibilities of welding observation with regard of sielding gas
MAG welding is characterized by very rapid processes in extreme condition of electric arc. To describe welding is necessary to use sufficiently quick equipment. Especially in the transition region ...
Tungsten coatings and free standing parts
Brožek, Vlastimil; Ctibor, Pavel; Matějíček, Jiří; Mušálek, Radek; Weiss, Z.
2013 - English
Tungsten powders, 20 – 100 µm in size, were melted in the jet of thermal plasma generated by a water-stabilized spray system WSP®. The molten tungsten was deposited on steel and graphite or boron nitride substrates, whereas the spray-ability itself was tested as well as cohesion with other substrates. One of the goals of this experimentation was to gain skills for covering variously shaped walls of nuclear fusion devices (Tokamaks). Also spraying of free-standing tungsten bodies was realized, by means of substrates easily machainable-out after deposition, as graphite and BN. Other option consists of covering a tungsten mesh or plates armored with tungsten wires. Protection of tungsten against oxidation in the plasma jet was a problem to be solved – the best results were gained with shroud gas, Ar with 7% hydrogen, and simultaneous placement of the substrates into graphite cells. The whole spray process was maintained to avoid temperatures over 700°C at which the oxidation is
Keywords:
tungsten coatings; tungsten filters; plasma spraying; shrouding; tungsten plasma spraying; protection against oxidation
Available at various institutes of the ASCR
Tungsten coatings and free standing parts
Tungsten powders, 20 – 100 µm in size, were melted in the jet of thermal plasma generated by a water-stabilized spray system WSP®. The molten tungsten was deposited on steel and graphite or boron ...
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