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 °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.