ITER is an international fusion experiment presently under construction in Cadarache, France, which aims to achieve 500 MW of fusion power form the deuterium-tritium fusion reaction. The environment within the reactor will be among the most hostile in any device built by man, with plasma-facing wall materials being exposed to steady heat fluxes exceeding 10 MW/m2, neutron irradiation, and both hydrogen and helium plasma.
One particular concern is the potential for material modification during exposure to the plasma. Helium is insoluble in tungsten, so helium from the plasma will precipitate out in the form of nano-scale bubbles. At higher temperatures the surface of the sample can be altered dramatically through the formation of surface pits, or fine fuzz-like nano-structures growing from the sample surface. Over time these processes of material modification may have a detrimental impact on the material’s thermal conductivity, mechanical strength, resistance to thermal shocks, and erosion rates. It is therefore essential that we are able to accurately characterise these structures, and from there develop a detailed understanding of how these structures will evolve within the fusion environment.
To measure these nano-structures we are using a technique called “Grazing Incidence Small Angle X-ray Scattering” (GISAXS). Here, the sample is exposed to an x-ray beam to produce a scattering pattern which provides information about the nano-scale structure of the material. Students will have the opportunity to work at the forefront of the international fusion materials community with cutting edge techniques and potential exposure to international researchers working in the field as well as utilisation of landmark Australian research infrastructure such as the the Australian Synchrotron.
Potential projects include:
- Studying nano-bubble formation in tungsten or other metals by exposing samples to helium or mixed helium-deuterium plasma.
- Growing “nano-fuzz” on metals under different conditions to better understand how it forms.
- Monte-Carlo methods to analyse GISAXS diffraction data.