SURFACE-TENSION AND DENSITY-MEASUREMENTS FOR INDIUM AND URANIUM USING A SESSILE-DROP APPARATUS WITH GLOW-DISCHARGE CLEANING

The sessile-drop method is used to measure the surface tension and density of liquid indium and uranium under high vacuum. Measurements are made over the temperature range 156-500 degrees C for In and at the melting point for U. Surface oxides are efficiently removed with a glow discharge system. Drop profiles are captured by photograph and processed using nonlinear regression to yield the surface tension and density. In this regression procedure, normal distances from calculated profiles to data points are minimized. For indium, the density and surface tension measurements yield p(mp) = 7.05 X 10(3) kg/m(3), dp/dT = -0.776 kg/m(3) .degrees C, and gamma(mp) = 0.568 N/m, d gamma/dT = -9.45 x 10(-5) N/m .degrees C. The results for uranium at the melting point are p(mp) = 17.47 x 10(3) kg/m(3) and gamma(mp) = 1.653 N/m.