Use of MgB2 Superconductors for Excitation Field in Synchronous Machines. Part II: Inserts

The flux trapping capabilities of bulk magnesium diboride disks have been investigated in part one on the basis of both measurements and numerical simulations. In this companion paper, a different fabrication technique of MgB2 magnets for synchronous machine excitation is illustrated and evaluated. In order to overcome the limitations to the field trapping capabilities that have been highlighted by the experiments, two different layouts are built and tested. The first is made by subdividing the disk into concentric rings, and the second is made by embedding circular or spiral circuits inside steel disks. The magnetic field trapping characteristics of these MgB2 inserts are studied.