Putting next generation fusion materials on the fast track

Lead Research Organisation: University College London
Department Name: Physics and Astronomy


Enormous numbers of energetic neutrons are released when helium is produced by the fusion of deuterium and tritium at high temperatures, as in our Sun. This promises to solve the World's long-term energy needs if a controlled version can be carried out on Earth. JET at Culham has been one of the leading experimental reactors for magnetically confined fusion using gaseous plasmas, and has been an important step towards designing the international thermonuclear experimental reactor, ITER. UK fusion technology is now on the fast track and will demand a new generation of materials for commercial reactor construction. The selection of materials for ITER has been based on those available some years ago, but there are trade-offs in deciding whether to use high temperature metals that are resistant to plasma erosion but liable to be damaged by radiation and also contaminate the pure plasma, or to use light elements that are toxic (beryllium) or more easily eroded and may absorb significant amounts of tritium fuel (graphite). We want to establish a materials capability for the next generation, and in particular to exploit our capability in diamond films as a route to designer carbons as plasma-facing wall materials. This proposal intends to coat carbon tiles with diamond on a large scale, in order to lower the erosion rates, dust formation, and tritium absorption, by using the unique properties of diamond, namely high temperature stability, radiation resistance, high atomic density and unsurpassed chemical stability in the presence of hydrogen plasmas. This solution enables the preferred use of low atomic number plasma-facing materials. Computational modelling of carbon structures will complement the experimental programme in optimising the chemical and physical structure of a composite functional material exposed to radiation. If successful, this approach would enable reactors to operate for longer periods before component replacements and without compromising the tritium inventory.


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Duffy DM (2010) Fusion power: a challenge for materials science. in Philosophical transactions. Series A, Mathematical, physical, and engineering sciences

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Dunn A (2011) A molecular dynamics study of diamond exposed to tritium bombardment for fusion applications in Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

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Itoh N (2009) Making tracks: electronic excitation roles in forming swift heavy ion tracks. in Journal of physics. Condensed matter : an Institute of Physics journal

Description In this project we studied the suitability of diamond as a plasma facing materials for fusion power plants. One of the main challenges associated with the development of fusion power is the design of materials that can withstand the the very harsh environment. The material needs to survive an extremely high heat flux and the bombardment by particles of hydrogen and helium that escape from the plasma.

Our part of the project was involved with modelling the interaction of hydrogen with diamond surfaces. We found that the hydrogen atoms induced damage to the diamond surface and transformed it to amorphous carbon. It also interacted with the surface and resulted in small hydrocarbon molecules being ejected from the surface.

The modelling work was done in collaboration with experimental groups at Heriot-Watt University and FOM. These groups subjected diamond components to a range of radiation types and characterised the resulting damage.

The objectives of the project were largely met.

Some further research was carried out by our collaborators on the potential for diamond as a plasma facing material. However in recent years the interaction with hydrogen isotopes has been identified as a significant problem and it is no longer seen as a good candidate material for this function.
Exploitation Route The majority view of the fusion community currently is that all carbon based materials would be problematic as plasma facing materials because of the tendency to interact with hydrogen isotope, which would result in the tritium fuel being deposited as hydrocarbons on the vessel wall. Diamond is not, currently, believed to be a fruitful direction for plasma facing material research.
Sectors Energy

Description The main impact of the research was the support of experimental data that suggested that diamond is not an ideal material for the divertor region of a fusion reactor.
First Year Of Impact 2010
Sector Energy