Construction of a Preliminary Calibration Loop in Preparation for a Fast Flow Lithium Plasma Facing Component Testbed

The reactor-relevant design of Plasma Facing Components (PFCs) is a large challenge in the path to commercial fusion. Among the available PFC designs, flowing liquid metal PFCs have grown in popularity due to the self-healing nature of their surface, which may extend PFC lifespan and reduce downtime for PFC replacement. Liquid lithium is one of the primary liquid metals of interest due to its promotion of the low recycling regime, low atomic number, and Edge Localized Mode (ELM) suppression. To further research into ‘fast-flow' (fluid speed >1m/s) liquid lithium PFCs, a lithium loop is being designed at the University of Illinois Urbana-Champaign (UIUC) as part of the Department of Energy Milestone Project.

The liquid metal loop at UIUC will be installed on the Hybrid Illinois Device for Research and Applications (HIDRA) stellarator, which can create toroidal fields of up to 0.5 T. Moving magnet pumps (MMPs) and direct current (DC) conduction flowmeters will be used to drive the fluid and measure the flow rate, respectively. The pumps are designed to rotate 9” diameter magnet discs containing N42 Neodymium magnets up to 1800 rpm using a 3 hp motor. The pumps are designed to ideally push the lithium to over 30 psi and 400 g/s.

The MMPs and DC flowmeters are novel constructions for UIUC and therefore need to be tested. A preliminary loop will be built to calibrate the pumps and flowmeters and assess their operating limits. The information gained from this test loop will aid in the implementation of the components in the final loop.