Controlled magnetic confinement fusion offers the possibility of an inexhaustible supply of energy with zero greenhouse gas emissions. At the very high temperatures needed to initiate a fusion reaction, the fuel (a mixture of deuterium and tritium) exists in the plasma state.
Magnetohydrodynamics (MHD) is an electromagnetic fluid model of magnetized plasmas, with applications ranging from solar flares through to fusion experiments in the laboratory. In an ANU/international collaboration, a new MHD model is being developed: multi-region relaxed MHD (MRXMHD). This is based on the use of a topological invariant called the helicity, which is used in conventional plasma relaxation theory to constrain the evolution of a relaxing plasma towards a minimum energy state. In MRXMHD the plasma is divided into multiple regions, each with its own helicity invariant, thus allowing the description of a richer variety of phenomena.
It is already known that reconnection ("tearing") of magnetic field lines is compatible with helicity conservation, thus allowing the spontaneous formation of helical states, called "tearing modes", during relaxation. The project is to relate the onset of tearing mode instability in MRXMHD to the multi-tearing Delta' formalism of Dewar and Pletzer (developed in an earlier ANU PhD project) and to use this to model recent experimental results in Reversed Field Pinches (RFPs), a class of toroidal fusion devices.
During the project the student can expect to develop skills in:
- Plasma equilibrium and fluid dynamics theory
- Applied mathematics, in particular using differential geometry and dynamical systems theory
- Computation and visualization