HYSTERESIS AND AVALANCHE BEHAVIOR OF HELIUM IN ANOPORE AND NUCLEPORE

Superfluid He-4 exhibits hysteretic behavior in the porous material Nu clepore due to capillary condensation, and one observes avalanches in the draining for a narrow range of chemical potential. We have demonst rated that the avalanche behavior involves pores distributed at a low density across the entire sample, and that avalanches are enabled by t he superfluid film. We present results which compare the behavior of s uperfluid He-4 in Nuclepore to its behavior in Anopore, a porous membr ane having non interconnected pores, and draw conclusions concerning t he role of the superfluid film and the pore intersections.