A phenomenon in bulk HTS that leads to greatly expanded applicability to electromechanical devices

摘要

Recent studies of pulsed-Zero Field Cool Magnetization (P-ZFCM) of high temperature superconductor (HTS) trapped field magnets (TFMs) have reported a new phenomenon, a sudden giant field leap (GFL), accompanied by a decrease in the activation ratio, B-A/B-T,B-max, from similar to 4.0 to 1.0. Here, BA is the P-ZFCM pulse magnitude required to activate the TFM to its maximum magnetizable field, BT,max. Experiments are reported here on the temperature increase, Delta T, caused by P-ZFCM and on a new record trapped field of 4.54 T achieved by that method of magnetization Delta T is measured indirectly to avoid difficulties inherent in direct methods. P-ZFCM heating, accompanied by GFL, is found to decrease B-T,B-max by only 3.25% and increase the TFM temperature by less than 1.07 K. In addition, data presented here show that the GFL increase in field is not caused by an induced electric field, a mechanism used in all prior theories of HTS magnetization, but by a new phenomenon resulting from a high magnetic field, which has not yet been successfully described theoretically. The resulting TFMs are applicable to electromechanical devices, such as motors and generators, and should greatly reduce the volume and cost of such applications while sharply increasing torque density. Published under license by AIP Publishing.