This title appears in the Scientific Report :
2000
Please use the identifier:
http://hdl.handle.net/2128/20586 in citations.
Modellierung der Plasma-Wand-Wechselwirkung und des lokalen Teilchentransportes in der Plasmarandschicht von Tokamaks
Modellierung der Plasma-Wand-Wechselwirkung und des lokalen Teilchentransportes in der Plasmarandschicht von Tokamaks
In fusion research the interaction of the plasma with the Walls is one of the critical issues. On the one hand the plasma induced erosion limits the lifetime of wall components . On the other hand eroded particies can be transported into the core plasma where they dilute the fusion plasma and iead t...
Saved in:
Personal Name(s): | Kirschner, A. (Corresponding author) |
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Contributing Institute: |
Institut für Plasmaphysik; IPP |
Imprint: |
Jülich
Forschungszentrum, Zentralbibliothek
2000
|
Document Type: |
Book |
Research Program: |
Wandkonditionierung und Plasma-Wand-Prozesse |
Series Title: |
Berichte des Forschungszentrums Jülich
3741 |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
In fusion research the interaction of the plasma with the Walls is one of the critical issues. On the one hand the plasma induced erosion limits the lifetime of wall components . On the other hand eroded particies can be transported into the core plasma where they dilute the fusion plasma and iead to energy losses due to radiation . To achieve ignition conditions the dilution as well as the cooling has to be reduced to a minimum . Potential wall canditates under discussion are low-Z materials with low atomic numbers like carbon and high-Z elements with high atomic nurnhers like tungsten . High-Z materials exhibit in comnparison to low-Z ones the advantage of Small physical sputtering yields . On the other hand one has to consider the high radiation potential due to the high atomic number . Especially carbon-like materials are suitable for high he gt flux conditions . Due to their thermodynarnical properties they do not suffer even under extreme power loads . However, low-Z materials exhibit high sputtering rates and in the Gase of carbon-like materials there exists the additional erosion channel of chemical erosion . Particularly at low terperatures, where the physical erosion yield deereases, the chemical erosion determines the erosion behaviour of these materials. The main emphasis of the present thesis is the question to what extent high-Z and low-Z; materials are suitable materials for wall components in fusion machines . For this, simulation calculations with the three-dimensional Monte-Carlo code ERO-TEXTOR [Kög97a] were carried out . This code is able to model the different plasma wall interaction processes like erosion, deposition and redeposition (i . e. deposition of eroded particles) as well as the loeal transport of eroded particies in the scrape-off layer . Tungsten was chosen as a typical high-Z element. The simulated erosion and deposition behaviour of a spherically shaped tungsten limiter under the influence of a deuterium plasma with carbon as main impurity showed the influence of the electron temperature and density . Especially an inerease of the electron density results in higher redeposition rates for tungsten as well as for carbon, which was previously deposited fror the Background plasma . Independent of the plasma conditions the redeposition rates for tungsten are clearly higher than for carbon . This differenee is particulary obvious with regard to prompt redeposition, i . e. redeposition of eroded particies during the first gyration loop . Due to the high redeposition rates it is possible to achieve acceptable lifetimes of tungsten wall elements by choosing suitable plasma conditions . The simulated carbon deposition of tungsten liniiters exposed to the scrape-off-iayer is in good agreement with experimental observations . Significant differences can be exp ained with simplifications inside the ERO-TEXTOR code |