Peak Heat Flux Density of Superfluid He II in Insulated Vertical Channels with Closed Ends and Wells

Abstract

In some situations, cooling by superfluid liquid helium (He II) may be advantageous for ac operation of superconducting solenoids [1] and during dissipative processes associated with flux motion [2]. The surface of the dissipative device can be kept cool by direct thermal contact with the liquid He II up to a critical thermal load (peak heat flux). Subsequently, film boiling sets in. Theoretical predictions of the peak heat flux for liquid He I (and other ordinary liquids) break down as soon as the temperature drops below the λ point (T λ = 2.172°K). This behavior is caused by He II superfluidity, as pointed out by Sydoriak and Roberts [3] on the basis of open-channel studies. The ideal-evaporator model proposed by these investigators [4] predicts a monotonic decrease of the peak flux as T is lowered towards absolute zero. In contrast, the experimental data show a maximum at about 1.9°K and may be up to one order of magnitude larger than the values predicted by the evaporator model [5]