Transient heat transfer and recovery behavior of superconductors

Transient heat transfer from bare and coated copper surfaces to saturated liquid helium was measured with a time constant of ∼ 5 μsec. In another experiment recovery of a superconducting wire after a temperature excursion was studied. The results show a large difference between bare and coated surfaces, latter recover at higher surface heat fluxes. While the recovery time of the coated surface is a smooth function of the temperature excursion, that of the bare surface exhibits a discontinuity, being higher for a small disturbance.