Tungsten was irradiated with different ion species (H, D, He, Si, Fe, Cu, W) at energies between 0.3 and 20.3 MeV to two different calculated damage levels of 0.04 dpa and 0.5 dpa. Samples were exposed to a low-temperature deuterium (D) plasma at 370 K to decorate the radiation defects. D retention was studied by nuclear reaction analysis using the D( 3 He, p)α reaction and by thermal desorption spectroscopy. For tungsten irradiated by light ions (H, D, He) the depth profiles as well as D desorption spectra show clear differences. On the other hand, tungsten irradiated by medium-to high-mass ions (Si, Cu, Fe, W) to identical dpa values shows similar D depth profiles and nearly identical D desorption spectra, i.e. the D retention is comparable. Since the large differences in the primary recoil energy distribution due to different incident energies of the different ions (Si, Cu, Fe, W) do not result in a different D retention, we assume that neutron irradiation of tungsten in a future fusion reactor will result in a similar D retention as in tungsten damaged by medium-to high-mass ions. Irradiation with ions with a mass of 28 amu (Si) or higher seems to be a suitable proxy for investigating the influence of displacement damage by neutrons on D retention.

The differential cross sections for the nuclear reaction D( 3 He, p) 4 He were determined at reaction angles of 135°, 144.5° and 175° for 3 He energies in the laboratory frame between 0.25 and 5.6 MeV. The uncertainty of the determined cross sections is between 4.1% and 5.9%. The results were compared with theoretical predictions for the cross sections [M. Nocente et al., Nuclear Fusion 50 (2010) 055001]. For energies below 1 MeV the theoretical values deviate significantly from the experimental data. For higher energies the theoretical predictions agree well with the experimental data.

Single crystalline tungsten was irradiated by the medium-mass ion Si with 7.5 MeV and high mass-ion W with 20.3 MeV up to a calculated peak damage level of 0.04 dpa and 0.5 dpa. The obtained dislocation structure of the damage zone was investigated by transmission electron microscopy and systematically compared with each other. Bright-field kinematical images were taken under four different two-beam diffraction conditions g= -200, 020, -110, 110 close to the [100] zone axis. The observed damage depth and damage peak position is in good agreement with the SRIM calculated damage depth profiles. The dislocation structures were investigated at the region of the damage peak because there the damage levels are comparable. In both irradiations (Si and W), the dislocation structures were similar. At the low damage level of 0.04 dpa dislocation loops and dislocation-loop clusters were found. The size of the dislocation loops in the W-irradiated tungsten sample was up to 20 % higher than for the Si-irradiated sample. At the high damage level of 0.5 dpa a dislocation network consisting of dislocation-loop chains and dislocation lines was found for both irradiations. The dislocation line density was about 12 % higher for the W-irradiated sample. Through comparison of the damage zone to SRIM damage depth profiles it was found that the transition from dislocation loops and dislocation-loop clusters to an ordered dislocation network takes place at about 0.08-0.1 dpa. Despite the large differences in ion mass and irradiation energy the dislocation structure were very similar.