Correlation between deuterium retention and microstructure change for tungsten under triple ion implantation

Abstract

Triple ion (C+, D2+ and He+) implantation onto a tungsten substrate was performed to investigate the hydrogen isotope and microstructure behavior under fusion conditions. The results are compared to the ones from dual ion (C+ and D2+) implanted tungsten. It was found that the TDS spectrum for the triple ion implanted sample is quite different from that for the dual ion implanted sample and the deuterium retention decreased when He+ was added to the incident beam indicating that the helium prevented deuterium trapping. TEM images show that dislocations and dislocation loops were introduced in tungsten in both the dual and triple ion irradiation experiments and helium bubbles were formed on the triple ion implanted tungsten. After heating up to 1173 K, not only the dislocations and dislocation loops but also helium bubbles remained on the triple ion implanted sample, but the dislocations and dislocation loops were moved and/or annihilated on the dual ion implanted sample. The formation of a WC layer was inhibited in the triple ion implanted sample.