DYNAMICS OF MOBILE LIQUID BUBBLES IN HELIUM MIXTURE CRYSTALS

We describe systematic heat-transport measurements of a 7.5% He-3-He-4 solid mixture coexisting with the liquid at temperatures near 1 K. We observed that under a temperature gradient, macroscopic liquid bubble s appear and move through the solid. Visually, this phenomenon resembl es boiling. However, in our case the bubbles are formed and subsequent ly move from the cold side towards the hot side of the experimental ce ll. The bubbles move with a speed that depends linearly on the tempera ture gradient. We present a model explaining the motion of the bubbles as resulting from the dynamics of superfluid mixtures. A possible mec hanism of bubble formation is discussed.