Nonlinear Dissipative Effects of Stable Current Penetration into Technical Superconductor

This article discusses characteristic features of energy dissipation from the eigenfield of transport current upon its stable penetration into a technical superconductor. The regimes of partial and complete penetration are considered. Analysis of dissipative states of a superconductor is compared with the results following from the theory based on the critical state model. It is demonstrated that the critical state model, according to which there is no electric voltage in superconductors at currents lower than critical one, underestimates heat release from the eigenfield of transport current and does not allow calculating correctly the energy losses in superconductors with actual current–voltage characteristics in the range of subcritical currents that can exist upon complete current penetration into superconductor. The error of the critical state model depends on the pattern of increase in current–voltage characteristic, the rate of current input, the transverse size of superconductor, and the critical current density. At the same time the self-similar and the zero-dimensional approximations make it possible to determine the energy losses in superconductors with actual current–voltage characteristic from varying eigenfield of transport current with sufficient accuracy upon both its partial and complete penetration.