RETENTION AND DESORPTION OF IMPLANTED DEUTERIUM OF HIGH-Z PLASMA-FACING MATERIALS

Thermal desorption after D-2(+) irradiation from high-Z materials (W a nd Mo) has been compared with radiation induced microstructural evolut ion to investigate the details of retention and desorption of the impl anted deuterium and underlying microscopic mechanism of the processes, The experimental results indicate that residual impurities act as maj or trapping sites for implanted deuterium independently of the ion ene rgy for relatively low dose. The trapped deuterium is desorbed in two steps between 470 K and 660 K for high purity Mo, and 400 K and 650 K for high purity W, In the case of Mo damaged heavily at room temperatu re (1 x 10(22) ions/m(2)), small cavities trap deuterium and give a la rge desorption stage at around 640 K. Radiation induced dislocation lo ops also trap the implanted deuterium effectively.