Progress and issues in PWI studies of tungsten for ITER

Advantages of tungsten as plasma-facing materials for ITER tokamak are based on its properties such as high melting point, low sputtering yield and low hydrogen adsorption. However, these properties will change during the plasma-wall interaction (PWI). In the present chapter, we deal with four important issues on PWI: damaging of metals by the helium plasma, surface modification by the formation of a mixed-material deposition layer, neutron damage and tritium storage and melting and crack formation by the heat pulse. Effects of these issues on the life and performance of tungsten-based plasma-facing components, the impurity release into the core plasma, the fuel particle balance and the tritium inventory are discussed. (J.P.N.)