Innovative Surfaces for Controlled Flow of Molten Lithium

The economic, environmental, and strategic benefits associated with the development of fusion energy are numerous, but they cannot be realized until new technology is developed to allow operation under high heat flux conditions. Bathing the wall of a fusion reactor plasma-facing component in a liquid metal is a viable approach for accommodating high heat fluxes and for removing hydrogen isotopes. This project will develop an enabling technology for the controlled flow of molten lithium. In this approach, microtextured tungsten and rhenium coatings, consisting of hundreds of thousands of dendrites per square millimeter, will act as a high-efficiency wick to stabilize liquid metal flow, despite the existence of strong magnetohydrodynamic forces. Phase I demonstrated the ability of the textured tungsten and rhenium coatings to wick molten lithium. The wetted coatings retained the molten metal in the face of strong jxB forces. In Phase II, additional wetting experiments, using a variety of techniques, will be conducted. Specimens will be characterized, fabricated, and ultimately tested in the Lithium Tokamak eXperiment (LTX) reactor at the Princeton Plasma Physics Laboratory (PPPL). Commercial Applications and other Benefits as described by the awardee: The new coatings can be applied to smooth surfaces and to the interior of porous bodies, such as refractory metal foams, for improved retention of the molten metal. Once demonstrated in the LTX reactor, the proposed technology should be applied in the near term to larger fusion reactors such as NSTX and ITER. As additional fusion reactors are brought on line, the textured coating technology will be incorporated into them as well.