Experimental Investigation on Conduction-Cooled Fast-Ramping Layer-Wound (RE)BCO Superconducting Magnet for Magnetic Refrigeration

Abstract

Magnetic refrigeration requires a strong magnetic field and its alternation for the magnetization and demagnetization processes. A conduction-cooled (RE)BCO coil was designed and fabricated to exert the maximum central magnetic field of 3.5 T with a field homogeneity of 90% on the magnetic refrigerant bed for an adiabatic demagnetization refrigerator (ADR) operating between 22 and 20 K. The polyimide tape insulated (RE)BCO tape conductor was wound on the stainless steel bobbin with standard layer-wound method whose outer diameter and thickness were 25.4 and 0.3 mm, respectively. The fast-ramping (RE)BCO coil was conductively cooled by a GM cryocooler to approximately 20 K. The (RE)BCO coil winding has a novel thermal drain structure to withstand the high thermal loads during alternating current (AC) operation which consists of high purity copper strip arrays installed between the inter-layers of the coil winding. Alternating magnetic field was stably generated with the peak of 3.0 T at the current of 130 A (10.5 A s(-1)). In this paper, the technical issues regarding to the fast-ramping conduction-cooled (RE)BCO coil itself and the integrated operation with the magnetic refrigeration system are discussed