Effect of Plasma-material Interactions on Near-surface Degradation & Tritium Retention in Additively Manufactured W, Advanced Tungsten (W) Alloys and Composites

A funded 3.5-year UK PhD studentship is available at the University of Birmingham with a tax-free stipend. The project is collaborated with Forschungszentrum Jülich in Germany, CEA-Cadarache in France, Dutch Institute for Fundamental Energy Research (DIFFER) in the Netherlands, Tokamak Energy and the UKAEA’s Tritium Fuel Cycle division.

Background:

Fusion energy demonstration depends upon high-performance materials availability due to unprecedented operating conditions envisaged for structural materials & plasma-facing components. In the plasma-facing regions, such as armour and divertor, W is the primary material candidate due to its favourable characteristics such as high melting point, low impact on plasma stability, and high thermal conductivity. However, W is brittle which gets progressively worse under neutron irradiation. More importantly, plasma-material interactions (PMI) will cause severe near-surface degradation of W due to unprecedented plasma particle fluxes comprising of deuterium, tritium, helium and other impurities (>10²⁴ particles.m^-2s^-1 in the divertor) over a wide temperature range with simultaneous steady-state heat loads (up to ~15 MW/m²), going to several GW/m² transient loads. PMI also causes enhanced near-surface tritium retention in W, which is deleterious to fuel sufficiency requirement. Lately, accident tolerance of W is being questioned where under the loss of coolant accident volatile products such as toxic radioactive WO₃ can form. If loss of vacuum occurs, WO₃ mobilisation beyond the primary containment could occur. To address some of the challenges described above, novel materials based on W-Cr system, potassium (K) doped W, W_f/W_m composites and additively manufactured (AM) W alloys are being developed. While the W-Cr system targets improving accident tolerance, K-doping improves radiation tolerance and W_f/W_m composites target imparting pseudo ductility. Further, AM of W alloys is being pursued as a pathway to improve properties while generating complex shapes with fine-tuned microstructures. Currently, little is known regarding PMI induced degradation of these materials, which is a major technological gap.

Proposed Work Scope: This study will focus on understanding the effect of plasma exposure via PMI experiments, on the degradation of advanced W alloys, composites and AM W. To understand the interplay between different plasma species, and the further impact of impurity seeding that is critical for benchmarking erosion rates, the materials will be exposed to deuterium ion plasma and mixed plasma scenarios at PSI-2 over a wide temperature range. Post exposure examination (PEE) of the sample microstructures will be performed using the university’s extensive electron microscopy and advanced analytical characterization capabilities. Use of advanced data analytics, including potential application of AI/ML is envisaged.

Supervision and International Collaborations: You will be based at the University of Birmingham, and will be collaborated with researchers from Jülich, DIFFER and CEA-Cadarache. This project will involve multi-national collaborators, and so you will have a unique opportunity to work with renowned experts from world-recognized institutes in Germany, France, the Netherlands, and the UK.

Who we are looking for:

A first or upper-second-class degree in an appropriate discipline: materials science and engineering, nuclear/chemical/mechanical/aerospace engineering, physics, plasma-physics, condensed-matter physics. No prior experience is mandatory. Some exposure to microstructural characterisation, hydrogen materials interaction and/or, fission/fusion basics would be advantageous.

A self-motivated, inquisitive, genuine and driven individual.

Contact:

Please contact Professor Arunodaya Bhattacharya – a.bhattacharya.1@bham.ac.uk to discuss your motivation. Include the following: CV and transcripts.

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