Simultaneous bombardment with helium, hydrogen, and heavy ions to simulate microstructural damage from fission or fusion neutrons

Effect of pre-implanted helium on void swelling evolution in self-ion irradiated HT9

“…Although the number density of voids continued to increase with helium, this effect was superseded by a decrease in void diameter. Suppression of void diameter and increase in number density by pre-injected helium was observed by Farrell et al [4], who attributed this behavior to the early nucleation of voids, which then acted as neutral sinks for vacancies and interstitials. This effect would be further exacerbated by large numbers of He stabilized bubbles/voids failing to reach the critical size for continuous growth.…”

“…Pre-implanted helium suppressed void swelling, relative to that of co-injection, by suppression of void diameter from 15 to 12 nm. However, He levels were not the same ( A study by Farrell et al [4] examined variation in void behavior between pre-injected, single beam irradiation, and co-injected irradiation of Fe-17Cr-17Ni-2.5Mo-0.005C-0.1Si-0.01Ti up to 70 dpa at 625°C. Irradiations were performed with 4 MeV Ni ++ , 4 MeV Ni ++ pre-implanted with 0.2-0.4 MeV 4 He + at room temperature or 4 MeV Ni ++ co-injected with 0.2-0.4 MeV 4 He + .…”

“…Helium created in-reactor by transmutation reactions has been postulated to affect void nucleation and/or growth behavior [4,5], although the precise mechanism is not known. It is especially unclear what effect, if any, helium has on the growth of voids in F-M alloys, since these alloys have been shown to be very swelling resistant [1][2][3].…”

A helium-induced shift in the temperature dependence of swelling

“…the Oak Ridge National Laboratory triple ion irradiation facility which was recently upgraded from its previous dual ion capability. The principle and practice of this improved facility are described briefly in two recent short papers [8,9], and full details and results of the present experiments will be made available in a laboratory report. In essence, the facility consists of two Van de Graaff particle accelerators, one of them delivering the displacement damage beam of k MeV S8 Ni ions and the other one simultaneously implanting alpha parHcles and deuterons from a source consisting of a mixture of helium and molecular deuterium.…”

JANNUS: A multi-irradiation platform for experimental validation at the scale of the atomistic modelling

“…They evidenced that high temperature He pre-implantation of Ni irradiated by self ions enhances the formation of voids and reduces their average diameters in comparison with simultaneous He/Ni irradiation. Then, Farrell, Lewis and Packan showed that during the dual or triple irradiation of steel, hydrogen synergistic effects are rather limited on the evolution of microstructure [2]. In France, Lévy, Gilbon and Rivera clearly demonstrated that sequential and dual beam irradiation of 316 steel (Ni and He ions) could lead to substantially different results in terms of swelling amplitude [3].…”