Naomi Mburu is a DPhil Candidate in Engineering Science at the University of Oxford focusing on heat transfer for nuclear fusion reactors as a Rhodes Scholar. She is also a former NextProf participant and NERS visitor.

Abstract
The development of robust plasma facing components (PFCs) is one of the outstanding challenges to the realisation of electricity generation from nuclear fusion. The PFCs within a commercial tokamak fusion reactor will need to withstand extreme thermal and mechanical loads as well as neutron irradiation for extended periods of time. Currently, liquid metals are being studied as a promising replacement for solid wall PFC’s because they are self-healing and have the ability to absorb plasma discharge that would otherwise reduce the efficiency of the core plasma. Extensive theoretical and experimental work is still needed to fully characterize the tokamak environment on liquid metal flows. Preliminary theoretical work has shown that under fusion-relevant conditions, the poloidal magnetic field has a much stronger effect on the thin-film flow of liquid metal than the toroidal field. However, the comparative magnetohydrodynamic (MHD) effects on the flow of thin-film liquid metal through poloidal and toroidal magnetic fields have yet to be experimentally quantified.

This talk details the design of an experimental facility to characterize the flow of a free surface, thin-film (1 mm) of liquid metal in the presence of a poloidal and toroidal magnetic field of the order of 0.2 Tesla. A Helmholtz Coil is designed and manufactured to produce a region of roughly uniform magnetic field, and the liquid metal Galinstan is used as the working fluid. The preservation of the Hartmann number (Ha), Reynolds number (Re) and aspect ratio (ε) at fusion relevant conditions guides the development of the physical parameters of this experiment. The experiment is designed to allow for high resolution liquid metal surface and depth analysis, and eventually to explore the added effects of temperature gradients on liquid metal flow in thermoelectric magnetohydrodynamic (TEMHD) conditions.