USING LIQUID-HELIUM TO STUDY FLUID INTERFACE COALESCENCE EFFECTS

The impact of a liquid drop on a liquid surface has been studied exten sively with acoustic techniques and high-speed imaging in the past dec ade. Experiments show that only a small range of drop parameters cause entrained bubbles. Numerical studies give an empirical formula for th e boundaries of the entrainment region. The formula depends on the dro p size, impact velocity, etc. Experimental studies have been done in w ater, and it would be of interest to study the same phenomenon in a ve ry different fluid, such as liquid helium. We are performing experimen ts with liquid helium using new high speed acoustic and optical probes . Methods to systematically form droplets of liquid helium have been s tudied. Preliminary acoustic signals showed traces similar, but not id entical, to those observed in water.