Plasma Facing Component Laser-Based Surface Microtexturing For Liquid Metal Wetting, Improved Heat Transfer, Safety and Control

Use of liquid lithium as a plasmafacing component for fusion reactors is ideal due to its low atomic number (Z=3) vs. tungsten (Z=74), keeping plasma hot with low radiative emission and minimal density depletion, and ability to flow over surfaces to remove hydrogen/impurities and keep a surface cool with bulk liquid flow and highheat transfer properties. The primary challenge is handling, control, and manipulation of liquid lithium, particularly controlling its wetting properties on surfaces to manage where the liquid metal will go and not go. This challenge is being addressed through this small business innovative research project to use laser based microtexturing to control how the liquid metal contacts the surface, its adhesion and wetting properties. By adjusting laser wavelength, pulse shape, duration and profile, different micro and nano textures can make the surface either super hydrophobic (liquid repelling) or super hydrophilic (liquid absorbing). This direct modification transforms only a thin (microns) layer of material leaving bulk properties intact. The laserbased processing approach is scalable for postprocessing on large surfaces and complex shapes needed for advanced fusion reactor development. Basic proofofconcept was demonstrated in Phase I by increasing the critical wetting temperature of lithium on stainless steel from 325C to 400C. In Phase II, the parameter space will explore in detail leading to a journal publication and science contribution to this emerging field. A prototype material texturing tool will be developed. A lithium PFC component will be designed and fabricated based on the selected Phase II laser texturing parameters for basic testing and future validation at a fusion facility. The primary benefit to the public will be commercialization of a new processing method and tool to engineer materials for superior interface heat transfer, fluid flow, and fluid safety properties. Two commercial applications have been identified that will be vetted and explored in Phase II.. The laser process is well suited for volume manufacturing and can be directly applied onto a prefabricated part or component prior to installation or use, such as a large area divertor plate.