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

Surface microtexturing can be used for enhanced heat transfer capabilities at liquid-solid or gas-solid interfaces to improve convection, decrease boundary layer size, change liquid flow properties, and affect the general fluid adhesion (wetting) on the material surface. Recent research has shown that sub- nanosecond laser pulses on metallic surfaces (e.g. stainless, zirconium, etc.)can produce microscopic features. By adjusting laser wavelength, pulse shape, duration and profile, different microtextures 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. This proposal is being submitted to explore if this laser texturing process could be applied on fusion reactor materials to control liquid metals, change flow properties, improve heat transfer, improve wetting or create regions of non-wetting and improve flowing across large substrates. Of particular importance will be research: (1) to make regions highly wetting to liquid metals by direct changing of the material surface property and (2) to change regions to be hydrophobic to inhibit liquid metal flow, spillover or movement. Both are important for safety and the combination can limit liquid metal loss on a PFC during a transient event. This project will also explore the technique for use on PFC backsides for improved heat transfer and cooling from liquids or gases, such as improving microturbulence, reduce boundary layer and stagnation effects and increase the convective coefficient for heat removal. 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. Spill over beyond fusion PFCs is envisioned for high-heat flux cooling applications, such as electronics cooling, building HVAC, boilers, fission reactors, etc. with application to all energy production sectors. 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.