Instabilities in Technical Superconductors

Characteristic regularities of development of thermoelectrodynamic processes in current-carrying elements of superconducting magnet systems are discussed. It is shown that, under certain conditions, the process of penetration of a magnetic flux can acquire an avalanche-like character, much like the development of a chain reaction of neutron fission. As a result, the inevitable increase in temperature can destroy the superconducting state of the current-carrying element. Analysis of nonisothermal states is compared with the results of the existing theory that neglects stable finite overheating before the occurrence of unstable states. The mode of penetration of an external magnetic field into a thermally insulated superconductor, when the errors of isothermal approximation are the most significant, is considered.