Nuclear and Fusion could potentially replace fossil fuels and complement renewable energy sources by providing an alternative source of electricity. Tungsten is of particular interest for use as a plasma facing material due to its high melting point and resistance to swelling. Producing a material with an optimal concentration of grain boundaries, with a high number of interfaces that can act as efficient defect sinks, could provide a pathway to the production of radiation resistant materials. Chapter 1 outlines the nature of the current global energy crisis, and the role that nuclear and fusion could play in the future. The material challenges associated with the production of future nuclear and fusion reactors are detailed. Finally, relevant theoretical and experimental methodologies are reviewed. In chapter 2 we highlight the details of the methodology that underpins the simulations carried out in this work. Chapter 3 is focussed on the simulation of collision cascades in bulk tungsten. We first outline the simulation details and post-analysis methodology. We then present the results of our simulations in bulk tungsten, including the distribution in space of defects and displacements. From these distributions, we are able to identify regular cascades, channelling, and sub-cascade-like behaviour. In chapter 4, we introduce interfaces to the system by embedding a tungsten nanoparticle in bulk tungsten. We introduce the concept of local lattice orientation, which allows us to track the relative size of the nanoparticle and bulk regions throughout the simulation. In chapter 5, we expand upon the work in chapter 4 by introducing additional embedded nanoparticles into the system. We use two different systems in our simulations, in which the embedded nanoparticles are arranged in a bcc structure and in an fcc structure. In chapter 6, we focus on collision cascade simulations in two highly ordered polycrystal structures, which are based on repeating bcc and fcc unit cells. We find that initiating collision cascades at different distances from an interface does not have a significant impact on the production of defects in these structures. We also find that large vacancy clusters are much less likely to form in these structures than the embedded nanoparticle systems.
| Date of Award | 13 Dec 2023 |
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| Original language | English |
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| Supervisor | Marco Molinari (Main Supervisor) & Jonathan Hinks (Co-Supervisor) |
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