Onset of superfluidity far from equilibrium: dynamical effects on the correlation length

Nonlinear heat conduction has recently been measured near the superfluid tr ansition in pure He-4 at very low heat flux Q. Since both dynamic effects a nd gravity limit the divergence of the superfluid correlation length near t he transition at low-Q, these measurements must be repeated in the microgra vity environment in order to observe the dynamic effects in isolation. Comp arison of the microgravity data to similar data obtained on Earth will prov ide experimental insight into the effect of gravity on this nonlinear condu ction region at low heat flux when theoretical predictions are lacking. Whi le some measurement advantages exist in the microgravity laboratory, it is the study of the direct effect of gravity on the nonlinear conduction measu rements that motivate the microgravity need. (C) 2000 Published by Elsevier Science B.V. All rights reserved.