Congratulations Asad!

Congratulations to Asad Hussain who has recently successfully defended his thesis at viva. Asad is a University of Manchester student on the Fusion CDT, supervised by Professor Paul Mummery.

Asad’s thesis covered two topics: Synergistic Effects of Neutrons and Plasma on Materials in Fusion Reactors & Relaxation of Merging Magnetic Flux Ropes in Fusion and Solar Plasmas.

The first topic deals with materials in a fusion reactor and examines how neutron damage affects material in a fusion reactor, with focus on how this is important for plasma damage. This is important since currently there are no continuous 14 MeV neutron sources but it is likely to be an extreme problem in a fully functioning fusion reactor. The methods used are simulation based and include neutron transport, primary event analysis and molecular dynamics. It found that the neutron damage by 14 MeV neutrons is restricted to back scatter events within the surface (first 20 microns). A molecular level investigation using molecular dynamics (a classical approximation for the movement of atoms in a lattice) was also done to investigate the statistical variance of nuclear damage based on direction and angle of impact.

The second topic deals with the relaxation of magnetic flux ropes and directly deals with the coronal heating problem. The coronal heating problem concerns itself with why the temperature of the surface of the sun is as high as it is. Simulations are not computationally mature to handle the scale required. Therefore, an analytical approach was chosen. A relaxation model was developed which shows good approximation to simulation results of merging magnetic flux ropes with a pre defined instability. Subsequently, work was done to establish the physical processes involved in relaxation. This was done by examining magnetohydrodynamic (MHD) simulations of two flux ropes, one unstable and one stable. It was found that there is is a clear distance at which merger does not occur any more. Furthermore, a critical current seems to be a requirement at the edge a stable flux rope. The successful deployment of the relaxation model allows for it to also be readily available for use with instabilities inherent in fusion reactors (Edge Localised Modes, sawtooth crashes).