An injector device for producing clean-surface liquid metal samples of Li, Ga and Sn-Li in vacuum

A vacuum-compatible-injector device, that allows the extrusion of clean-surface samples of low-melting-point liquid metal into a holder kept in vacuum, is reported. Clean-surface samples of liquid lithium, gallium and 80 at.% tin-20 at.% lithium alloy have been demonstrated for the purpose of their use in plasma/liquid metal interaction experiments. As a result of the use of the injector, subsequent experiments are free of the influences of surface-oxide material. The elimination of surface oxide facilitates wetting and spreading of clean-liquid lithium on a stainless steel substrate holder (AISI 304). Further, the spreading of the liquid is more rapid with increasing holder temperature. At temperatures above 500 deg. C, evaporative loss of the lithium is substantial under vacuum conditions. However, pressurizing the vacuum system with argon gas to ∼1 atm significantly suppresses evaporation while maintaining chemically-inert conditions that keep the lithium clean, and facilitate a reasonable wetting rate