Heat Flow from Solid to Liquid He II Due to Inelastic Processes of Phonons Interaction

The quantum theory for description of creation of phonons in superfluid helium by a solid heater is developed in this work. This problem first came up after experimental discover of temperature gap on He II–solid interface (Kapitza gap). The first theoretical description of this problem was given by I.M. Khalatnikov (Introduction to the Theory of Superfluidity, Benjamin, New York, 1965 ). Despite this there is no complete agreement between theory and experiment until now. A new approach to solve this problem is proposed. The main idea is account of not only elastic mechanism of creation and annihilation phonons (Khalatnikov in Introduction to the Theory of Superfluidity, Benjamin, New York, 1965 ), but also a number of inelastic processes on He II–solid interface. The proposed model allows to calculate the explicit expressions for heat flux from heater to superfluid helium. It was shown that heat flux due to inelastic processes under certain conditions can be in order of magnitude to the flux due to elastic processes.