Heat flow at the niobium-superfluid helium interface : Kapitza resistance and superconducting cavities

By measuring the temperature jump in the presence of a heat flux across niobium disks surrounded by He II, we determined the Kapitza resistance, R sub(k), for different surface roughness and bulk purity. The experiments were conducted from 1.5 K to T sub( lambda ), under saturated vapour pressure. The influence of foreign atoms due to the presence of Ti near the interface was also investigated. The importance of R sub(k) on the efficiency of superconducting cavities is discussed.