Supervisor/s: Aneeqa Khan, Ed Pickering, Paul Mummery (University of Manchester)
This project will focus on the analysis and development of tungsten diamond composites for fusion applications, building on existing work with UKAEA and INFLPR where single layers of tungsten are being deposited on CVD diamond.
ITER divertor plasma facing components (PFCs) are engineered to withstand 10 MW m-2 of steady-state surface heating. For comparison, the value is approximately 1 MW m-2 for a spacecraft heat shield during re-entry, 10-80 MW m-2 for an arc welder, and 50-150 MW m-2 for a cryogenically cooled rocket engine nozzle.
For the last 25 years, progress in fusion has largely relied on the use of fine grain graphite and carbon fiber composites in the high heat-flux regions, where the carbon technology was adapted from the fission and aerospace industries. More recently, the carbon surface has been enhanced with high performance tungsten thin films (10-200 microns) in order to increase erosion resistance.
Over a similar timeframe, diamond from CVD has become readily available. A UKAEA led research programme from 2007-2010 included: (i) a 5 mm thick boron-doped plate prototype exposed to high heat-flux electron beam testing (Figure 1), and (ii) thin films exposed to plasma in several fusion devices. In 2022 a new program started funded by UKAEA as part of SBRI to produce tungsten coating on CVD diamond in collaboration with INFLPR.
CVD diamond is of interest because diamond has many relevant properties that are often best-in-class compared to all other materials:
- isotropic thermal conductivity 5 times higher than copper at room temperature
- very low thermal expansion,
- the above combine to give diamond unparalleled thermal shock resistance,
- sublimates instead of melting,
- low chemical reactivity with hydrogen in a gas environment,
- forms strong carbide chemical bonds with many metals, including tungsten,
- high tensile strength, and
- good resistance to neutron radiation damage.
The goal is to build on existing work where tungsten is being deposited on CVD diamond. This will contribute to the development of a multi layered composite tungsten diamond material in order to:
a) reduce chemical reactivity,
b) increase the erosion resistance to physical sputtering,
c) marginal improved ductility at elevated temperatures, and
d) quasi-self-repairing, since the diamond erodes until a new tungsten layer if the surface film is lost.
If the films are thin enough (< 10 microns approximately), then the bulk properties of the composite should be similar to diamond.
This project will work on developing tungsten diamond composites and potentially a multi-layer composite and test it under fusion relevant conditions.
This PhD project will develop experimental materials analysis skills (e.g. electron microscopy), as well as communication, scientific writing and analytical skills.
The project will be based at Manchester but will involve travel to other facilities to carry out experiments.
This project is offered by the University of Manchester. For further information please contact Aneeqa Khan at Aneeqa.email@example.com
This project may be compatible with part time study, please contact the project supervisors if you are interested in exploring this.
Figure above: 1: 5 mm thick boron-doped CVD diamond.