Flowing liquid metal walls as plasma facing components: an integrated approach for a multifunctional system

Liquid lithium breeding blankets are a critical enabling technology for the operation of deuterium-tritium nuclear fusion power plants, providing with the necessary fuel for the reaction to take place. However, one can envision the liquid metal as providing with other critical functions such as neutron shielding and energy extraction. In this work we outline the path from conceptual design of a liquid metal wall subsystem intended to fulfill these various functions, to practical implementation. This implies an increase in Technology Readiness Level (TRL), a qualitative scale of the level of maturity of an industrial product. We define this metric as applied to Liquid Metal Plasma Facing Components and define a roadmap of successive experiments that will allow to progress several levels in this scale. Identified challenges include structural corrosion at fusion relevant temperatures due to the liquid metal flow, the use of active control to achieve an objective flow configuration using the electromagnetic forces resulting from injected electric current in the presence of a magnetic field, and proper distribution of lead pebbles intended to multiply neutron production. We describe recent numerical and experimental efforts that address these issues, and describe the roadmap of technology demonstrators necessary to build on the path towards a fully realized power plant. In this work we give an overview of several work streams that illustrate the multidisciplinary nature of the design and operation of these experiments. We first show results on high temperature static corrosion studies. We then propose a numerical methodology that allows to simulate injected current in a liquid metal flow and use it to design a magnetic levitation experiment. We describe a methodology that predicts the trajectories of solid pebbles, and find that design and control is possible via acting on the electromagnetophoresis force. Finally, we introduce a methodology for assessing the risk of free surface instabilities based on Linear Instability Analysis which accounts for system size.