Stabilization of liquid tin surfaces under D plasma irradiation by a capillary porous system

[Display omitted] •Comparison of free Sn surfaces and capillary porous systems (CPS) under D plasma erosion.•Free Sn surfaces are catastrophically unstable at high temperatures.•A CPS has a strong stabilizing effect on D-plasma-exposed Sn.•Upwelling of Sn to CPS surface under D plasma irradiation prevents dry-out, but also promotes bubbling. Liquid metal divertors are discussed as a potential alternative to divertor components made entirely of solid materials such as tungsten. However, liquid metal interaction with H isotope plasmas poses entirely new challenges, including the stability of the liquid surface. In this article, the interaction of low-temperature D plasmas with both free liquid tin surfaces, and the liquid metal confined in a capillary porous system (CPS) is presented. Free surfaces showed intolerable instabilities due to formation of gas bubbles in the melt, as opposed to a strong stabilizing effect of the CPS. A tendency of liquid tin to well up and entirely cover the surface of the CPS may be beneficial in terms of quickly re-establishing a tin surface after depletion by transient overloading. On the other hand, this appears to counteract efforts to fully suppress superficial bubble formation and bursting, and the resulting ejection of tin droplets by designing a CPS with very small pores.