Retention and permeation properties of deuterium in tungsten under irradiation of the D–He mixture plasma

Abstract

Tungsten (W) was selected as the plasma facing material in the ITER divertor region because of its high melting temperature and thermal conductivity and low sputtering erosion yield. Therefore, it is crucial to understand the behavior of hydrogen isotopes in W contained in the diverter wall material. The effects of the D–He mixture plasma on the retention and permeation properties of deuterium (D) in the W material were investigated using a linear plasma device TPD-Sheet IV. D or He mixed D (D + He) plasma was used, and ITER-grade W was used as the sample. The permeation property of D in W was investigated using a Ti plate as the D storage material, which was mounted behind W. The ion density in the D–He mixture plasma was measured using an Omegatron mass analyzer. The retention amount of D in W increased with the pure D plasma flux. On the other hand, the retention amount D in W was constant with increasing D–He plasma flux. At the same time, the retention amount of D in Ti increased with the D–He plasma flux. The incident flux of D–He mixture plasma affected the permeation of D in W.