Experimental measurements of helium retention in flowing liquid lithium

The Flowing Liquid Surface Retention Experiment (FLIRE) has been built and designed at the University of Illinois at Urbana-Champaign to provide fundamental experimental data on the retention and pumping of He, H and other species in flowing liquid surfaces. These measurements are critical to the development of advanced plasma-facing components (PFCs) that apply flowing liquid metals to mitigate high heat loads encountered in the divertor region of next-step fusion reactors. The FLIRE facility currently uses an ion beam source, which injects ions into a flowing stream of liquid lithium. Its design allows the liquid lithium to flow between two vacuum chambers that become isolated from each other when the lithium flows. Recent results show retention of helium in flowing liquid lithium at 250-300°C to be of the order 10^-4 and diffusivities of 10^-4 to 10^-3 cm²/sec.