An Active Controllable Demagnetization of Closed-Loop HTS Magnet and its Distributed 2.5D H-Model

Closed-loop high temperature superconducting (HTS) magnets have great potential to be used in many fields due to their abilities to be operated in persistent current mode. However, in emergency rundown, they are required to get demagnetized actively and controllably. In this paper, an active controllable demagnetization of closed-loop HTS magnet by flux pump with thermal switches is proposed and investigated. The Joule heat dissipated and the transport current in the magnet during demagnetization is calculated numerically. Besides, in order to improve the calculation speed, a distributed 2.5D H-model of the magnet is suggested, in which the computing tasks are divided into two coupled parts: a 3D model and a 2D axisymmetric model, and are deployed on two different computing nodes. Experiments are carried out to verify the rationalities of the introduced demagnetization method and the distributed 2.5D H-model. The results shows that the proposed demagnetization method can realize active-controlled demagnetization of a closed-loop HTS magnet rapidly without generating too much heat, and, compared with H formulation, the suggested model can effectively reduce the calculation time.