Fundamental Investigation of Liquid Rubidium and Liquid Lithium Contamination

The increasing interest in possible applications of alkali metals in space technology is creating new demands in the area of liquid alkali-metal handling technology. The presence of contaminants in alkali-metal fluids can exert deleterious effects on thermophysical properties, corrosivity, and handling characteristics. This paper reviews the properties of pure rubidium and lithium and describes the extent and source of typical contamination. A current experimental investigation of the role of contamination in liquid rubidium and liquid lithium systems is discussed. An example of the rate o-f diffusion of atmospheric oxygen through a vent pipe into rubidium is given, and experimental evidence is cited for the influence of dissolved oxygen on the melting point, viscosity, and pumping characteristics of liquid rubidium. Based on the melting point depression data, it is confirmed that oxygen contaminant, in low concentrations, exists in liquid rubidium as rubidium monoxide.