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. A way to confine the hot plasma is by applying a strong magnetic field.

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/ Princeton Plasma Physics Laboratory 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.

MRxMHD, and its numeric implementation through the supercomputer SPEC code developed by Princeton Plasma Physics Laboratory, has been applied to describe a rippled boundary perturbed field of the US DIII-D tokamak (http://link.aip.org/link/doi/10.1063/1.4765691?ver=pdfcov) , and the spontaneous helical state of RFX-mod (http://dx.doi.org/10.1103/PhysRevLett.111.055003). Opportunities exist to apply this code to describe sawteeth reconnection, and new data from a reverse field pinch which constrains the rotational transform profile (https://doi.org/10.1063/1.5038430), and the fully helical state of Heliotron J plasmas.

The project is suitable for third year special projects through to Honours and Masters.  Suitable project extensions to a PhD are also possible.

Illustrative Poincéare sections of double helical axis (left) and single helical axis (right) states of RFX-mod.

The solutions are predicted minimum energy states using the MRxMHD SPEC code.