Flux and fluence dependent helium plasma-materials interaction in hot-rolled and recrystallized tungsten

Abstract Tungsten is the primary candidate for plasma-facing materials (PFMs) in a magnetic fusion energy (MFE) devices such as ITER due to its high melting point, excellent erosion resistance, and low sputtering yield. However, tungsten will suffer from heat, neutron irradiation, large flux (10 22 -10 24 He/m 2 s)- low energy (tens of eV to hundreds of eV) helium and hydrogen ion exposure, as well as microstructure evolution (such as recrystallization). We have exposed hot-rolled and recrystallized tungsten to 65 or 80 eV helium ions with a flux of 0.5 × 10 22 or 5 × 10 22 He/m 2 s to total fluence from 0.6 × 10 24 to 4 × 10 24 He/m 2 at a temperature of ≈1100 K. The results show that recrystallized tungsten samples exhibit a roughened surface morphology in certain grains with orientations close to , while hot-rolled tungsten samples still maintain the smooth surface under all helium-ion exposure conditions. All the samples exhibit relatively shallow helium bubble penetration (