Behaviors of Deuterium Retention and Microstructure Change of Tungsten Simultaneously Implanted with Carbon and/or Helium Ions

Abstract

Recent studies of deuterium (D) retention and microstructure behaviors of tungsten simultaneously implanted with carbon ion (C + ) and/or helium ion (He + ) are reviewed. Implantation of deuterium ion (D2 + ) was performed by simultaneous implantations with C + ,H e + and a mixture of C + and He + using a triple-ion-implantation system, while D retention behavior was studied by thermal desorption spectroscopy. The D depth profile, microstructure changes, and chemical states of constituent atoms were observed by glow-discharge optical emission spectroscopy, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy, respectively. D retention was observed to be enhanced by both C + and He + implantations. After the simultaneous implantation of D2 + and C + , substantial D2 desorption was observed at temperatures higher than 600K. Following the simultaneous implantation of D2 + and He + , D retention increased to about five times that for D2 + implantation, while the D desorption temperature region was the same. However, in the case of triple-ion implantation, the accumulation of C on tungsten was suppressed, and the retention of D trapped by C was reduced. The D retention in triple-ion-implanted tungsten was considered to be suppressed by He + implantation. TEM observations suggest that most of the deuterium would be retained at grain boundaries and lattice defects such as vacancy clusters. [doi:10.2320/matertrans.MG201205]