A short-time physics problem in superconductivity: Stability against quench
This paper investigates the stability problem of superconductors against quench. Numerical Finite Element simulations are applied to calculate the distribution of transient temperature, critical current density and transport current in the conductor cross-section under a disturbance, here flux flow losses. Contrary to standard stability models, the focus of the paper is on situations very close to the superconducting/normal conducting phase transition. The obtained results demonstrate it is not realistic, even in thin films, to assume uniform conductor temperature under a disturbance. A method is suggested on how to predict the time and position of a quench when it is expected to occur in the conductor cross-section. Quench starts locally. Application of a microscopic stability model allows to describe continuous, not abrupt but very fast break-down of transport current in situations close to the phase transition.
Keywords: Numerical simulations; Finite Element method; Additive Approximation; BSCCO; YBaCuO; conductor temperature; superconductor stability, current transport