PhD Studentship: Transmutation Effects on Structural Integrity in Plasma-facing Tungsten Materials

Application open all year round?: No

Application deadline date: 15th January 2025

Supervisor(s): Prof. Enrique Jimenez-Melero

Main description:

Tungsten (W) is currently the frontrunner candidate as armour material for plasma-facing structural components in fusion tokamak technology. In particular, tungsten-based divertor components will experience high particle fluxes and steady-state heat loads ranging from ~8-20 MWm-2. These plant conditions will potentially generate local temperatures in W of ~800 °C or higher, together with predicted radiation-induced damage levels of ~0.1 dpa for permanent divertor components during ITER's end-of-life operation, and expected higher doses and dose rates in future, compact spherical tokamaks. Additionally, tungsten exposure to high-energy neutron fluxes from the D-T plasma reaction will trigger a cascade of transmutation reactions that over time generates an inventory of transmutant, heavy elements (e.g. Re, Os) and Helium (He) interstitials inside the tungsten structure. If He interstitials are present in bulk regions of W, they could agglomerate close to grain boundaries or radiation-induced lattice defects in the microstructure, forming bubbles or He-decorated voids that would deteriorate the material’s ductility and toughness. Those defect structures induced by radiation fluxes consist of (primarily interstitial-type) dislocation loops/tangles and voids formed by vacancy clustering, and can be altered by the simultaneous presence locally of transmutant elements and their segregation close to lattice defects. The relatively complex, synergistic transmutations-radiation damage interactions, and their impact on the material’s performance, remain largely unexplored, and most studies are limited to simplified material’s systems and environmental effects.

The aim of this project is to assess the impact of transmutant elements generated inside tungsten materials on the formation and evolution of damaged structures and bubble/void populations. And thereupon correlate those structural changes occurring in W under relevant service conditions to the material’s toughness and potential loss of integrity. In this project, you will be combining transmutation simulations to predict the isotope mixture in tungsten and related materials, and ion beams from accelerator-based sources to implant He atoms at different depths in the material and simultaneously trigger displacement cascades in the W structure. You will study the formation and evolution of damage structures, nano-clustering and bubble populations using advanced electron microscopy. Those microstructural changes can afterwards be correlated by mechanical testing to the performance and structural integrity of W materials containing fusion-relevant levels of transmutant elements in its structure.

During this project, you will be able to acquire a unique and valuable set of transferrable skills ranging from designing complex sample environments and experimental protocols, to programming and data mining, effective communication skills and project/time management. You will also gain in-depth knowledge about physical metallurgy, radiation effects and mechanical testing focusing on a material critical for fusion technology.

Funding notes:

A 3.5-year PhD studentship is available in the fusion materials group of Prof. Enrique Jimenez-Melero within the School of Metallurgy and Materials at the University of Birmingham, with a stipend of at least £18,622 per year. This project is funded by the UK Fusion Skills Programme run by the UK Atomic Energy Authority, with additional funding, project support and supervision by Frazer-Nash Consultancy.

Choose your subjects: Energy Technologies, Solid Mechanics, Structural Mechanics

Choose your subjects: Experimental Physics, Nuclear Physics, Solid State Physics

Choose your subjects: Metallurgy

Full name: Enrique Jimenez-Melero

Email: e.jimenez-melero@bham.ac.uk

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