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Ion-irradiation Studies on Tungsten : Recent Results on Radiation Damage and Deuterium Trapping

par Caroline CHAMPENOIS - publié le

vendredi 16 novembre 2018, à 11:30- service 322

P. N. Maya,
Univ. of Greifswald, Germany, Collaborator for IAEA CRP Project on Ion-irradiation of Tungsten, ITER-India (Institute for Plasma Research, Gandhinagar)

Abstract :
One of the key problems in projecting the current fusion devices to reactor-scale conditions is the handling of hot plasma in divertor region at the plasma-material interface. Not only the heat, but the high particle fluxes, longer exposure time and concomitant neutron irradiation makes the problem of estimating the survival/useful life of the component a challenging one. At present, tungsten has been widely used in place of carbon, to handle the high heat-flux zone. Despite its attractive properties, it is still not fully clear whether (a) it will store tritium in traps beyond the acceptable limit and (b) whether changes in its surface morphology will enhance erosion, due to, say, presence of helium or due to the way the traps are created. There is a need to simulate the damage using the ‘surrogate ion irradiation’ (using ion beams) and to understand the trapping of hydrogen isotopes. This is necessary as one cannot create conditions like that of fusion reactor. Actually, this area represents an ongoing global effort to build up a database for radiation damage and its effects. In general, these experiments will have to be complemented with tokamak plasma experiments. Furthermore, it will be necessary to explore the limits of extrapolation and essential differences between ion and neutron irradiation.

Recently, we have conducted a series of experiments to understand how the ion-mass and energy impact the defect structure. Experiments have been carried out 80 MeV gold and 10 MeV boron ions, apart from 250 keV helium and 100 keV deuterium. Extensive characterization using TEM and PAS has been done. D-trapping has been studies with SIMS and ERDA. TRIM and MD simulations have done to analyze the damage structure and defects. The talk also gives an overview of some of the key findings by other workers and how it correlates to the present work.

contact : Pascale Roubin

contact : Pascale Roubin


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