Investigations of Novel Liquid Lithium TEMHD Flow Geometries*

The use of flowing liquid lithium in plasma facing components (PFCs) has been shown to reduce erosion and thermal stress damage, prolong device lifetime, decrease edge recycling, reduce impurities, and increase plasma performance, all while providing a clean and self-healing surface. The Liquid Metal Infused Trench (LiMIT) system has proven the concept of controlled thermoelectric magnetohydrodynamic (TEMHD)-driven lithium flow for use in fusion relevant conditions, through tests at UIUC, HT-7, and Magnum PSI. One difficulty that arises is the phenomenon of lithium dryout, which exposes solid trench material due to strong local TEMHD acceleration in the areas with the highest heat flux. Novel geometries are being developed that maintain propensity for TEMHD flow while eliminating the risk of dryout. These include tailoring trench shaping to account for expected dryout regions, as well as large pore metallic foams, which aim to couple the surface stability of capillary porous systems with TEMHD flow. Maintaining a steady flowing liquid surface in the face of extreme heat fluxes is imperative for continued application of flowing liquid lithium PFCs. Designs, models, and experimental progress will be discussed.