Computations of superconducting magnet´s quench processes

Superconducting magnets applied in magnetic separators produce large magnetic fields. They can work nominally at elevated direct currents in steady states. A superconducting winding has zero electrical resistance at a temperature of 4.2 K. Sometimes, because of local disturbances, e.g. local mechanical or thermal stresses or rise in magnetic field, the winding becomes a resistive one and energy dissipation raises its temperature. A quench (superconductivity loss) in the coil can lead to an immense magnetic field energy discharge. The averaged critical parameters of the cryomagnet winding have been applied so far to analyze and design cryomagnets. The in-time variability of these parameters has not been usually considered. A new two-dimensional numerical model of the resistive zone propagation in the superconducting winding is developed. In the quench analysis not only the circuit electrical parameters such as resistance and inductance, but also the instantaneous local superconductor critical parameters, which are decisive for a transition of any winding point to a resistive state, are taken into account