Retention of ion-implanted deuterium in tungsten pre-irradiated with carbon ions

Deuterium (D) ion implantation and retention at room temperature was studie d in pure and carbon (C) implanted tungsten single crystals. Pre-implantati on with C was done at 40 keV and D implantation at 10 keV with the range co nfined in the carbon modified layer and at 100 keV with the range exceeding the carbon modified layer. The range distributions were investigated in si tu using 1 MeV He-3 ions analysing the energy distributions of alpha partic les from the D(He-3, p)alpha reaction while the total amount of retained D was obtained from the p-integral. The range distribution of carbon was obta ined from the backscattered He-3 energy distribution. C pre-impantation inf luences the D retention only if the range of the D ions is confined within the carbon modified surface layer. In this case, D diffusion beyond the ion range distribution does not occur and the retained D amount is smaller tha n in the pure W crystal. At D energies exceeding the carbon modified layer the retention occurs in the dislocation zone up to 1 mum and the total reta ined amount is the same for carbon implanted and pure W samples. (C) 2000 E lsevier Science B.V. All rights reserved.