Specific features of unsteady-state heat transfer to superfluid helium

The results of the experimental study of heat transfer from a cylindrical sample to superfluid helium under step pulse heat input are presented. The specific features of He II as a cryogenic agent are compared to those of He I. Accelerated crisis and transition region characterized by heat transfer surface superheat peaks are observed under certain conditions. The mechanism of the recorded processes such as superfluid turbulence state in He II, phase transitions He II → He I, He I → He vapour, interaction of the generated HeI phase and He II volume has been discussed