Observation of magnetic flux frozen in high conductivity metal during flux jumping in a type II superconductor

In the concentric arrangement of a superconducting tube and a high-conductivity aluminium cylinder, the magnetic flux variation arising from flux jumps occurred only within the superconducting tube itself, whereas the magnetic flux in the normal metal was almost completely frozen during the flux jumps. Provided that the magnetic flux was completely frozen in the normal metal, the energy released by a flux jump was calculated to be equal to a quarter that released by a complete flux jump. It was found that the magnetic diffusion time-constant was much larger than that given by $\text{L}{}^2\text{π}{}^2\text{D}{}_{\mathrm{m}}$.