The particle and heat loads to the plasma-facing surfaces of fusion plasmas constitute a major engineering problem in thermo-nuclear plasma devices. The choice of the plasma-facing materials is a crucial point in future devices, such as ITER (International Thermonuclear Experimental Reactor), which will determine issues such as the plasma facing components lifetime or the tritium inventory build up in the vessel, which must be limited for safety reasons. For the task of assessing the tritium inventory in a future fusion device the presentation will discuss the status of knowledge of processes involved. Implantation, retention and diffusion in plasma facing materials will be considered as well as surface erosion and co-deposition of tritium with eroded material. This involves processes ranging from sputtering, impurity transport, surface sticking of atoms and molecules and the final co-deposition of impurities together with hydrogen isotopes.
In order to address these issues, the European Task Force on Plasma wall interaction has been implemented in the frame of EFDA (European Fusion Agreement). The EU PWI TF brings together the efforts of 24 European associations in the following fields of investigation:
Material erosion and transport in tokamaks
Tritium inventory and removal
Transient heat loads on plasma facing components
Dust production and removal
Associated modelling and diagnostic development
The organisation of the EU PWI TF, its work programme and future milestones will be presented.
|