Flux Jumps in Nonideal Type-2 Superconductors. I. Theory of Flux Jumps in Slabs

A theory of flux jumps in a slab of a nonideal type-2 superconductor is developed by the use of a phenomenological theory of flux motion. To include explicitly in the theory the various quantities which are controllable experimentally, the temperature inside the slab is assumed to be approximately uniform. Then a flux jump is characterized by a catastrophically sharp rise of the temperature of the sample. The criteria for the occurrence of flux jumps are derived under such an assumption, together with the relation between the value of external magnetic field, at which a flux jump starts, and the sweeping rate of the external magnetic field. Various behaviors of flux jumps observed experimentally are reasonably explained by the present theory in a quantitative way.