HTS Magnet for Maglev Applications (1)— Coil Characteristics

We developed an HTS coil for maglev applications. The magnet consists of four persistent current HTS coils and is operated at a rated temperature of 20 K and a rated magnetomotive force of 750 kA for each coil. This paper describes the fabrication and test results of each persistent current HTS coil. The HTS coil consists of 12 single-pancake coils wound with four parallel Ag-sheathed Bi2223 wires and a persistent current switch (PCS) made of YBCO thin films. The coil is conductively cooled by a cryocooler to approximately 20 K. Persistent current operating tests for four HTS coils at 750 kA were carried out and current decay rates of 0.37-0.68%/day were obtained. Mechanical vibration tests up to plusmn15 (plusmn150 m/s
²
) were carried out to investigate the mechanical properties of the HTS coils. Temperature increasing tests up to 25 K, which is 5 K higher than the rated operating temperature and higher magnetomotive force operating tests up to 800 kA were carried out to investigate the thermal stability of the coils and check the mechanical strength of the coils