Irradiation effect on W surface with stress confinement under focus microwave plasma bombardment

摘要

W/Cu functionally gradient material (FGM) is a promising candidate for plasma facing component (PFC) used in ITER divertor due to its high heat capacity as well as excellent sputtering resistance. We have previously reported that such kind of FGM had very good thermal shock resistance. However, the irradiation effect of such composite is still not very clear. In order to investigate the effect of thermal stress on the irradiation damage of tungsten, bi-layered W/Cu composites with different residual stress distribution were designed and fabricated, and their irradiation behavior was investigated by focus H_2/He plasma manipulated in a microwave plasma device. The irradiated microstructures were characterized by FESEM and AFM; and the microscopic mechanism of irradiation damage of stress confined specimen was studied by the slow positron annihilation technique and X-ray diffraction. Finally UV-Vis spectroscopy and four-probe resistivity tester were applied to measure the photoelectric properties of bombarded samples. The results will provide some insight on the thermo-mechanical failure of PFC with stress confinement in the future operation. This work was partially supported by the JSPS-CAS Core-University program in the field of 'Plasma and Nuclear Fusion'.