Mass flux through solid 4He induced by chemical potential differences

Abstract

The thermo-mechanical effect and also direct mass injection have been used to create chemical potential differences between two reservoirs of superfluid 4He connected to each other through superfluid-filled Vycor rods in series with solid hcp 4He. An increasing DC flux of atoms takes place through the solid-filled cell with decreasing temperature below ≍ 600 mK That flux falls abruptly in the vicinity of 75–80 mK, but increases again at lower temperatures. These experiments, done in collaboration with M Ray, will be briefly reviewed as will our studies of the growth of solid 4He where it is seen that it is impossible to add density to a solid freshly made at 60 mK and samples freshly made near 60 mK do not allow mass flux, even when raised in temperature to 200 mK Solids created above ≍ 300 mK and cooled to 60 mK accept added density and demonstrate finite mass flux. Relationships to theoretical work and other solid helium work will be briefly discussed.