Lorentz Propulsion Hydrocyclone for In-Situ Centrifugal Separation of Li/LiH*

Plasma-facing liquid lithium is a promising sink for superheated helium ash in proposed nuclear fusion reactor concepts. With liquid metal (LM) lithium Plasma-Facing Components (PFCs), a Li/LiH liquid-solid mixture is generated, which must be pumped through intense magnetohydrodynamic drag to be separated prior to the fuel recycle of absorbed tritium. [1] A Lorentz force hydrocyclone is a high-throughput, unmechanical, and in-situ means of separating Li/LiH, operating on a reactor's existing B field and supplemental external current. An internal separation process will allow clarified lithium LM to be immediately recirculated into PFCs, with only a small, rich volume of LiH crystal slurry remaining to be pumped out. This will greatly reduce the volume of lithium needed for diverter operation, as the bulk exists in piping to the external separation system. However, hydrocyclone separation efficiency remains undetermined outside of promising COMSOL simulations, requiring experimentation to establish a physical baseline. We are constructing a modular hydrocyclone prototype at PPPL. A Lorentz thrust force is generated by an applied current of up to 900 Amps, and an electromagnet providing magnetic fields up to 0.3 Teslas. This arrangement will first characterize the efficiency of a proxy mixture separation, Galinstan and HfO2/WO3, under ideal thrust conditions where the magnetic propulsion is applied axisymmetrically. Separation efficiency will be measured and optimized through experimental variation of parameters such as cone length, and over/underflow ratio. These results will be foundational to implementing in-situ hydrocyclones for hydrogen isotope separation from LM, enabling the recycle of tritium fuel stock.