Working Magnetic Field Around the Rotating YBCO Disk of a Low-Power 2-Phase Bipolar Motor Entirely Based on Bulks

The design of a bipolar single-turn coil made of a YBCO bulk was proposed by the group of Electrical Application of Superconductors, at the University of Extremadura, to be an element for the design of a modular low-power two-phase axial-flux motor. The magnetic field is created by several of these elements strategically located in an arrangement that makes the field rotate in the space where a disk-shaped rotor made of YBCO is going to work. Part of the rotor pulling mechanism is due to the trapped magnetic field in the rotating disk and another part is due to the variation of the magnetic field on the surface of the disk, and how the magnetic field is screened by the disk. In this work we study the magnetic field in the space where the rotor works, before and after its placement, and measure the trapped magnetic field in the disk. We present the magnetic field maps obtained on planes located in both sides of the disk, and propose a distribution of the magnetic field lines that justify the measurements and show the screening effect of the disk.