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THERMAL AND MECHANICAL PROPERTIES OF TUNGSTEN COMPACTS PREPARED BY SPS
Nevrlá, Barbara; Vilémová, Monika; Matějíček, Jiří
2014 - English
Tungsten is a promising candidate material for use in the tokamak device aimed at future production of nuclear fusion power. Here, tungsten is intended for the application in the part called first wall,with the function of a heat-resistant plasma facing armor.In the present work,two fractions of tungsten powder (2 and 4 μm) were used to prepare two consolidated samples by spark plasma sintering (SPS),using a combination of pressure,temperature and electric power.This sintering technique produces samples of near theoretical density which is positive for the application.Tungsten compacts were then studied to determine some basic thermal and mechanical properties, namely thermal conductivity using the laser-flash method and hardness by Vickers test.The measurements were focused on thermal conductivity of the compacts because high thermal conductivity is crucial for the material of tokamak first wall,loaded by high heat flux from the plasma.High hardness is desirable for good resistance
Keywords:
spark plasma sintering; tungsten; thermal properties
Fulltext is available at external website.
THERMAL AND MECHANICAL PROPERTIES OF TUNGSTEN COMPACTS PREPARED BY SPS
Tungsten is a promising candidate material for use in the tokamak device aimed at future production of nuclear fusion power. Here, tungsten is intended for the application in the part called first ...
Global Power Balance in Non-Stationary Discharge Phases in the COMPASS Tokamak
Havlíček, Josef; Imríšek, Martin; Kovařík, Karel; Weinzettl, Vladimír
2014 - English
The global power balance between different input power and sink/loss channels is important for understanding of tokamak physics, particularly for various scaling laws. The power balance is measured easily during stationary discharge phases because the terms for both magnetic field energy and plasma thermal energy build-up can be neglected. However, many important events in tokamak plasmas occur during non-stationary phases of the discharge. This article describes, quantifies and discusses the terms of the global power balance, including time dependent parts, and exemplifies them on the typical ohmic discharge of the COMPASS tokamak.
Keywords:
tokamak; global power balance; power through separatrix; COMPASS
Available at various institutes of the ASCR
Global Power Balance in Non-Stationary Discharge Phases in the COMPASS Tokamak
The global power balance between different input power and sink/loss channels is important for understanding of tokamak physics, particularly for various scaling laws. The power balance is measured ...
Study of Alfven Eigenmodes in Tokamak COMPASS
Markovič, Tomáš; Stöckel, Jan; Seidl, Jakub; Melnikov, A.; Medvedev, S.
2014 - English
Having both MHD and kinetic character plasma Alfven eigenmodes are signicant not only on the eld basic plasma research, but also on the eld of magnetic connement fusion. An introduction to basic physical principles of Alfven eigenmodes under MHD approximation is provided. Presented results of recent experiments on COMPASS suggest occurrence of toroidal Alfven eigenmodes in this tokamak, which is further supported by preliminary linear MHD code simulations, althought more studies will have to be conducted in the future to further investigate presented modes therein.
Keywords:
Alfven eigenmodes; tokamak; COMPASS
Fulltext is available at external website.
Study of Alfven Eigenmodes in Tokamak COMPASS
Having both MHD and kinetic character plasma Alfven eigenmodes are signicant not only on the eld basic plasma research, but also on the eld of magnetic connement fusion. An introduction to basic ...
Plasma Boundary Reconstruction using Fast Camera on the COMPASS Tokamak
Háček, Pavel; Berta, Miklós; Stöckel, Jan; Weinzettl, Vladimír; Budai, C.; Szabolics, T.; Bencze, A.
2014 - English
Determination of the plasma boundary is an important task for safe operation of the tokamak and diagnostic systems as well as for correct interpretation of the measured data. Magnetic reconstruction codes routinely used to determine the shape of the plasma have a number of limitations which can make the reconstruction problematic. Recently, it has been demonstrated on several devices that it is possible to provide independent measurement of the plasma boundary by observation of the visiblelight emission using fast framing cameras. In the presented work, a single fast camera on the COMPASS tokamak was used for reconstruction of the optical plasma boundary, assuming a toroidally symmetric visible-light emission profile located in the edge of plasma. As a first result, application of the method on D-shaped COMPASS shot 7145 and its comparison with magnetic reconstruction from the EFIT code is given. Both methods show good agreement with average difference 0.5 cm.
Keywords:
plasma; tokamak; COMPASS
Fulltext is available at external website.
Plasma Boundary Reconstruction using Fast Camera on the COMPASS Tokamak
Determination of the plasma boundary is an important task for safe operation of the tokamak and diagnostic systems as well as for correct interpretation of the measured data. Magnetic reconstruction ...
On the Character of the Motion of Runaway Electrons in a Time Dependent Magnetic Field from 3D MHD Code JOREK
Papřok, Richard; Krlín, Ladislav
2014 - English
In our paper we describe our new particle tracking code and we present results of our simulations of trajectories of runaway electrons in a time dependent magnetic feld computed by non-linear 3D MHD code JOREK for the case of pellet injection on Tore Supra tokamak. We show that the character of the resulting motion is not a simple difusion process but rather a sum of a stable motion on the same radius and phases of rapid changes of radial position.
Keywords:
magnetic field; tokamak; plasma
Fulltext is available at external website.
On the Character of the Motion of Runaway Electrons in a Time Dependent Magnetic Field from 3D MHD Code JOREK
In our paper we describe our new particle tracking code and we present results of our simulations of trajectories of runaway electrons in a time dependent magnetic feld computed by non-linear 3D MHD ...
Properties of Novel Hybrid Water-Gas DC Arc Plasma Torch
Chráska, Tomáš; Hrabovský, Milan; Glanc, Aleš; Mušálek, Radek; Medřický, Jan
2014 - English
A new type of plasma torch with combined stabilization of electric arc by water vortex and gas flow is presented. This hybrid water/gas stabilization offers the possibility of adjusting plasma jet parameters within a wide range from high-enthalpy low-density plasmas typical for liquid stabilized torches to lower enthalpy higher density plasmas generated in gas stabilized torches. Moreover, gas flow in the cathode part protects a cathode tip and thus a consumable graphite cathode used in water-only stabilized plasma torches could be replaced by a fixed tungsten cathode. Examples of hybrid WSP torch utilization for high temperature application are given.
Keywords:
Water-Gas; Plasma Torch
Fulltext is available at external website.
Properties of Novel Hybrid Water-Gas DC Arc Plasma Torch
A new type of plasma torch with combined stabilization of electric arc by water vortex and gas flow is presented. This hybrid water/gas stabilization offers the possibility of adjusting plasma jet ...
Silicon carbide for chemical application prepared by SPS method
Brožek, Vlastimil; Kubatík, Tomáš František; Vilémová, Monika; Mušálek, Radek; Mastný, L.
2014 - English
Silicon carbide discovered more than 121 years ago has a wide usage in the mechanical engineering industry as well as in electrical engineering.It is an excellent abrasive medium as well as a construction material with high resistance to mechanical and chemical deterioration.Under standard condition, silicon carbide has no melting point (decomposes at 2700 °C – principle used for industrial production of silicon),thus the bulk form must be prepared in a composite form with a metallic, ceramic or polymer binder. This method is suitable for tailoring of mechanical properties; nevertheless,it does not produce SiC form applicable for laboratory purposes.Binder-free sintering of SiC is practically impossible, despite decreased chemical resistivity of the produced material. Pure SiC is insoluble in all acids except hydrofluoric acid.Reaction of SiC with HF is enabled only due to residual SiO2 created during the industrial production.However, SiO2 located between the planes of growth of SiC
Keywords:
silicon carbide; spark plasma sintering; silicon carbide corrosion; impurities in silicon carbide
Available at various institutes of the ASCR
Silicon carbide for chemical application prepared by SPS method
Silicon carbide discovered more than 121 years ago has a wide usage in the mechanical engineering industry as well as in electrical engineering.It is an excellent abrasive medium as well as a ...
Electric Probe Diagnostic of Supersonic Thermal Plasma Jet
Hurba, Oleksiy; Hrabovský, Milan
2014 - English
This paper describes how electric probes can be used as relatively simple and efficient tool for investigation of structure of flow field in thermal plasma jet at the low pressure. A boundary of plasma jet between nozzle of plasma torch and ambient air was investigated by means of array of moving electric probes. Were defined boundaries of the conducting region and their change with pressure change
Keywords:
thermal plasma; electric probes
Fulltext is available at external website.
Electric Probe Diagnostic of Supersonic Thermal Plasma Jet
This paper describes how electric probes can be used as relatively simple and efficient tool for investigation of structure of flow field in thermal plasma jet at the low pressure. A boundary of ...
Parallel Heat Flux Decay Length Study in the COMPASS Tokamak Using MWIR and LWIR Cameras
Vondráček, Petr; Horáček, Jan; Pánek, Radomír; Gauthier, E.
2014 - English
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.
Keywords:
Plasma diagnostics; infrared thermography; infrared camera; tokamak; near SOL
Fulltext is available at external website.
Parallel Heat Flux Decay Length Study in the COMPASS Tokamak Using MWIR and LWIR Cameras
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 ...
Properties of Filamentary Structures in Different Regimes of Plasma Confinement on the COMPASS Tokamak
Kovařík, Karel; Ďuran, Ivan; Stöckel, Jan; Adámek, Jiří; Spolaore, M.; Vianello, N.
2014 - English
A complex electrostatic-magnetic probe diagnostic, called U-probe, has been installed on the tokamak COMPASS recently. Probe composes of two identical towers. Each tower houses radialy separated 3 sets of 3D coils, a triple probe and a rake of six single Langmuir probes. We present measurements of electric and magnetic properties of the filamentary structures in the scrape off layer plasmas during different regimes of plasma confinement on COMPASS tokamak
Keywords:
U-probe; tokamak; COMPASS; plasma; Langmuir probes
Fulltext is available at external website.
Properties of Filamentary Structures in Different Regimes of Plasma Confinement on the COMPASS Tokamak
A complex electrostatic-magnetic probe diagnostic, called U-probe, has been installed on the tokamak COMPASS recently. Probe composes of two identical towers. Each tower houses radialy separated 3 ...
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