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+, He+ 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 600 K. 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.