The measurement of the surface tension and viscosity of undercooled melts under microgravity conditions

The viscosity of a liquid metal was successfully measured for the first time by a containerless method, the oscillating drop technique. This method also provides precise, non-contact measurement of the surface tension of the droplet. This measurement involves exciting and measuring surface oscillations on the molten sample; the natural frequency of the sample is determined by its surface tension and the damping of the oscillations by the viscosity. These measurements were performed in TEMPUS, a microgravity electromagnetic levitator (EML), on the Space Shuttle as a part of the First Microgravity Science Laboratory (MSL-1), which flew in April and July 1997 (STS-83 and STS-94). Some results of the surface tension and viscosity measurements are presented for Pd82Si18. Also presented are the results of some magnetohydrodynamic calculations performed in support of this and other experiments.