Behavior of a SnLi liquid metal eutectic on D-irradiated, porous tungsten substrates

Tungsten (W) is a common PFC material in the divertor due to its beneficial thermomechanical properties and high sputter threshold [1]. Under helium irradiation, W develops surface morphology such as fuzz. Liquid metals, such as tin-lithium eutectics, have been proposed as PFCs to combat W erosion and allow for a self-healing surface. Tin-dominant eutectics have lower evaporation rates than pure lithium due to increased binding energies, yet exhibit decreased D retention and Li surface segregation [2]. In prior experiments of SnLi coatings on fuzzy W substrates, the SnLi layer has been shown to protect underlying fuzz. Additionally, the liquid metal better adhered to a fuzzy surface than a smooth one [3]. Fuzzy W samples have been coated with a 95 at.{\%} SnLi eutectic and exposed to 250eV D ions at elevated temperatures and fluences of \textasciitilde 10$^{\mathrm{17}}$ cm$^{\mathrm{-2}}$ . Experiments will be conducted in the IGNIS facility, a multi-functional, \textit{in-situ }irradiation and characterization facility at the University of Illinois. \textit{In-situ }XPS will be used to elucidate irradiation-driven liquid metal behavior to identify surface chemistry changes. Additionally, \textit{ex-situ }SEM will be used to identify surface morphology changes. [1] Naujoks, et al. \textit{Nucl. ~Fusion}. Vol 36,~No. 6 (1996) [2] R. Bastasz et al. \textit{Fus. Eng. Des.} 72 (2004) 111--119 [3] E. Lang, et al. Not yet published. 2016