Tungsten is the main candidate for plasma facing material in the divertor zone of a thermonuclear reactor due to high melting temperature, high thermal conductivity and low sputtering erosion yield. However, its surface can be modified by "fuzz" nanostructure, which can form in linear simulators and tokamaks [1] under helium irradiation fluence as high as ~1025m-2, sample temperature in the range of 1000-2000 K and energy >20 eV. Such structure significantly changes the plasma-wall interaction balance, especially the interaction of plasma components with the surface.