Thermal conditions at the Gorter-Mellink counterflow limit between 0.01 and 3 bar

Abstract

Gorter-Mellink counterflow limits (at zero net mass flow) have been measured from 0.01 bar to about 3 bar in relatively wide ducts of rectangular (0.05 cm wide) and circular cross section (0.446 cm inner diameter). The observed limiting temperatures did not show metastable superheating of He II. Instead, they were controlled by the equilibrium state phase boundaries of the superfluid He4. Small departures from the related maximum temperature differences were in part caused by fluid acceleration and finite thermomter sizes, respectively. The measured limiting heat fluxes agree with the prediction based on the equilibrium state limits of the Gorter-Mellink temperature differences.