One of the greatest technical achievements of the 21st century will be the development of materials that can withstand the extremely harsh conditions within a fusion reactor. The Materials Program is engaged in a science-based effort to develop the scientific understanding of the damage mechanisms controlling performance-limiting phenomena of materials for fusion power systems. The program employs the full suite of experimental and computational tools to explore life limiting materials degradation phenomena in the fusion environment. Our overarching goal is to develop experimentally validated, physics-based, predictive models of complex material behavior that can be used to improve existing materials or to design better ones.
Since no fusion test reactor presently exists, we are using novel experimental techniques and computer simulations to understand the fundamental aspects of materials degradation under the radiation damage caused by high-energy fusion neutrons and the effects of large amounts of helium produced in the irradiated materials by nuclear transmutations. For example, an experimental technique has been developed to inject helium into a material while under neutron irradiation. Using this approach it is possible to explore the effects of helium on microstructural evolution under fusion relevant conditions. Figure 1 shows a typical microstructure produced by this method. While it is not possible to obtain bulk property information using this technique, it provides valuable data that is being used to inform and validate computational models of helium effects in fusion materials.