作者: Xiao-jing Zheng, Xiao-Fan Gou, You He Zhou

553

作者: X.L. Wu, W.M. Yang, S.H. Zhu, J.Z. Guo, T.N. Lu, J.L. Pei

摘要: The effect of magnet moving speed on the relaxation of the maximum levitation force of
YBCO bulk has been investigated. The experiment was carried out between a cylinder permanent
magnet and a single-domain YBCO bulk, and the levitation force was measured using a self-made
levitation force measurement system. It is found that the levitation force decreases with time after the
gap distance between the magnet and YBCO bulk reduced to 2 mm and kept for the test. It is also
found that the levitation force and its relaxation rate is different for different moving speed between
the magnet and the YBCO bulk, and the higher the moving speed, the greater the relaxation rate of
levitation force. However, the largest levitation force is obtained at an optimal speed, the higher the
levitation force, and the faster the relaxation of levitation force.

2103

作者: S.H. Zhu, W.M. Yang, X.L. Wu, J.Z. Guo, T.N. Lu, S.B. Xi

摘要: The effect of the moving speed between a permanent magnet and a superconductor on the
levitation force of single-domain YBCO bulk has been studied at liquid nitrogen temperature. It is
found that the levitation force is much different with different moving speed, the maximum levitation
force and the stiffness of the force-distance curve are increasing first and then decreasing with the
increasing of the moving speed and, there is a reasonable speed to get the maximum levitation force. It
is also found that the maximum attractive force is decreasing with the increasing of the moving speed.

2107

作者: Yu Zhu, Yu Liu, Ming Zhang

摘要: This paper proposed a new configuration of magnetic bearings used in magnetic levitation stages. The equivalent current sheet model is introduced to calculate the levitation force of the proposed magnetic bearing, and the experiment result validates the correctness of the calculation method. The relationships of structural parameters to the levitation force and axial stiffness are studied, which prove that the new magnetic bearing has larger levitation force with lower axial stiffness over the working stroke and could be applied in ultra-precision magnetic levitation stages.

2106

作者: Wen Feng Zhang, Guo Min Zhang, Dong Xia, Qing Quan Qiu, Zhi Qiang Yu, Lei Hu

摘要: t is important to simulate the levitation force and its relaxation with time for the designers in the process of designing a HTS (high temperature superconductor)-magnet levitation bearing. In this paper, FEM (finite element method) based on HTSs critical-state model using H formulation was introduced. In the zero field condition, the process of magnetization of a cylindrical HTS bulk was simulated. The result showed that, current would be induced when HTS bulk was put in the external magnetic field, and the induced current tried to prevent the change of the magnetic field in the HTS bulk. When the external field disappeared, HTS bulk trapped some of the field and the bulk was magnetized. HTS-magnet levitation models were built in both the axisymmetric field and the plane field. Forces and their relaxations with time were calculated. In the HTS-magnet levitation system, force faded with time and faded slower as time went on. The force was bigger when the HTS bulk was put closer to the magnet and relaxed a little more.

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