Novel methodology of homogeneous ion doping/damage of nuclear materials for structural characterization

Studies of radiation effects in nuclear reactor materials using ion irradiation in accelerators, instead of effort and time-consuming neutron irradiation are limited, in addition to the high dose rate effect, by the strictly peak nature of ion damage and implantation. To overcome the limitation of fixed ion ranges, a new methodology for uniform bulk ion irradiation of material samples using a software-controlled tilting target was developed and tested. For the verification experiment, a heat-resistant austenitic steel sample was uniformly irradiated with 3 MeV He ²⁺ ions to a dose of 0.1 dpa and a helium doping level of 1100 appm in the depth range from 1.8 to 4.5 μm. The dislocation-loop structure and gas porosity obtained as a result of irradiation and post-irradiation annealing were studied using TEM in cross-section geometry. The homogeneity of helium doping of the sample was verified by determining the specific surface area of helium porosity as a function of depth based on measurements of gas bubble diameters and foil thickness.