A FEM study of liquid lithium on a 〈011〉-oriented tungsten tip

Field electron emission patterns from a 〈011〉-oriented tungsten tip coated with a liquid lithium film were observed. For the deposition thickness between 20 and 120 nm, emission patterns suggested the formation of liquid cones on the facets of the tungsten surface. Changes in emission current and patterns with the tip voltage were qualitatively explained in terms of the space charge effect. Though the emission current decreased linearly with time in the rate of 1.5 μA/min, its fluctuation was lower than 1%. For a film thicker than 120 nm, only pulsed explosive emission was observed. When the polarity of the tip voltage was reversed, this beam source operated as a liquid metal ion source.