Thermomechanical and chemical properties of porous W/liquid Li hybrid systems as plasma-facing self-healing surfaces*

The environmental conditions at the plasma-material interface of a future nuclear fusion reactor interacting will be extreme. The incident plasma will carry heat fluxes of the order of 100's of MWm$^{\mathrm{-2}}$ and particle fluxes that can average 10$^{\mathrm{24}}$ m$^{\mathrm{-2}}$s$^{\mathrm{-1}}$. The fusion reactor wall would need to operate at high temperatures near 800 C and the incident energy of particles will vary from a few eV ions to MeV neutrons. A hybrid system, inspired by self-healing solid-state concepts, combines the ductile phase of liquid Li within a solid phase porous W. The liquid Li serves to control hydrogen retention and provide vapor shielding, within the framework of a tunable porosity to optimize edge plasma conditions [2]. Additionally, the porous interface can also provide for effective defect sinks for high duty cycle neutron damage. The surface chemistry of liquid Li on a porous surface varied with D irradiation is studied and its effect on retention. Prior results with refractory alloys have demonstrated effective wetting properties [3]. These hybrid systems, as well as traditional W samples, are bombarded with 500eV D$_{\mathrm{2}}^{\mathrm{+}}$ and Ar$^{\mathrm{+}}$ at 230$^{\mathrm{o}}$C and 300$^{\mathrm{o}}$C. The Li, O, and C XPS peaks were examined and compared to controls. Additionally, the porous W is characterized for thermo-mechanical properties.