The levitation force and stiffness enhancement of single domain GdBCO bulk superconductor by an axial background magnetic field

How to improve the levitation force (FL) and its stiffness between a permanent magnet and a REBCO bulk superconductor is one of the most key and attractive problems to be solved for practical applications. In this paper, we provided a novel hybrid magnet added superconductor system (HMS) to enhance the levitation force and the stiffness, the HMS sample is assembled by a single domain GdBCO bulk with an attached permanent magnet (PM) serving as an axial background magnetic field. The results indicate that (1) the FL increased first and decreased then with the increase of the PM diameter (dPM), the largest FL is achieved when the dPM approaches the diameter of the GdBCO bulk, FL has been improved up to 152% with a thinner PM; (2) the FL increased with the increase of the PM thickness and saturated at a certain value, FL have been improved up to 168% with a thicker PM; (3) the stiffness of FL has been improved up to 187% and 201% with the increase of the PM diameter and thickness; (4) the FL and its stiffness enhancement dependent on the positive trapped field of the field cooled HMS samples. The results are of great significance to improve the performance and stability of maglev systems, the mechanism for enhancing the levitation force and stiffness property has been investigated in details.