Influence of experimental methods on crossing in magnetic force–gap hysteresis curve of HTS maglev system

• Published in: Physica. C, Superconductivity Vol. 470; no. 22; pp. 1994 - 1997
• Main Authors: Lu, Yiyun, Qin, Yujie, Dang, Qiaohong, Wang, Jiasu
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-12-2010; Elsevier
• Subjects: Applied sciences; Crossing; Electronics; Exact sciences and technology; Heat insulation; High speed; HTS; Hysteresis; Hysteresis loop; Levitation; Levitation force; Low speed; Mathematical models; Melts; Movement; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Superconducting devices; Superconductivity; Heat insulation; Hysteresis loop; Crossing; Levitation force; HTS; Force measurement; Flux flow; Flux creep; Magnetic hysteresis; Iron alloy; Boron alloys; Permanent magnet; Maxwell equation; High temperature superconductor; Magnetic levitation; Neodymium alloy
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/j.physc.2010.09.003

The crossing in magnetic levitation force–gap hysteresis curve of melt high-temperature superconductor (HTS) vs. NdFeB permanent magnet (PM) was experimentally studied. One HTS bulk and PM was used in the experiments. Four experimental methods were employed combining of high/low speed of movement of PM with/without heat insulation materials (HIM) enclosed respectively. Experimental results show that crossing of the levitation force–gap curve is related to experimental methods. A crossing occurs in the magnetic force–gap curve while the PM moves approaching to and departing from the sample with high or low speed of movement without HIM enclosed. When the PM is enclosed with HIM during the measurement procedures, there is no crossing in the force–gap curve no matter high speed or low speed of movement of the PM. It was found experimentally that, with the increase of the moving speed of the PM, the maximum magnitude of levitation force of the HTS increases also. The results are interpreted based on Maxwell theories and flux flow-creep models of HTS.