文档介绍：郑州大学毕业设计(论文)
题目: 超导磁悬浮磁滞现象的动态理论研究
指导教师: 职称: 教授
学生姓名: 学号:
专业: 物理学
院(系): 物理工程学院
完成时间: 2011年5月20日
2011年 6 月 1 日
超导磁悬浮磁滞现象的动态理论研究
摘要
本文从磁通量子在变化外磁场中成核、穿透、钉扎并排出的角度,研究了二类超导体磁悬浮系统的磁滞现象,认为超导悬浮力来源于表面迈斯纳抗磁电流,和单个磁通量子涡旋分别与外场相互作用,并证明了涡旋密度梯度等效电流和外场的相互作用,本质上,就是所有磁通量子涡旋和外场相互作用的总和,而磁通涡旋从表面穿透和排出过程的不对称,和由于超导体不同几何形状所导致的几何势垒引起的的不可逆性,以及磁通涡旋在超导体内部运动耗散的能量,导致了二类超导体在变化外磁场中的磁滞现象,其中后者占据的比重远大于前者,进而精确计算了在永磁体产生的高度不均匀的变化外磁场中的悬浮力,得到了与实验相符的结果,为理解二类超导磁滞现象,更好地应用高温超导体提供了新的视角和基础。
关键词:二类超导,悬浮,涡旋,磁滞
Dynamic Theoretical Modeling on Type-II Superconductor
Levitation Hysteresis Phonomenon
Abstract
From the perspective of flux quantum nucleation, ration, pinning, and discharged in a changing external ic field, we simulated the dynamic response of Type II superconductors, specifically, type-II Superconductor ic levitation system hysteresis phenomenon, in the process of a permanent close to and away from Superconductor. We showed that the origin of superconducting levitation force is that, the surface Meissner current, ic flux quantum vortex interaction between external ic field, respectively. And we proved that macroscopic current due to the vortex density gradient interacting with the external ic field, essentially, is equivalent to all the flux quantum vortex interacting with the external ic field. The asymmetry due to the Bean-Livingston surface barrier, the irreversibility due to the geometric barrier as a results of superconductor different geometric shapes, in the process of the flux vortex ration and emission from the surface, and the energy dissipation due to flux vortex movement within the superconductor, results in the Type II superconductors levitation hysteresis in the changing external ic field, among which, the significance of the last one is much greater than the former two. And then we calculated accurately the superconductor levitation hysteresis curve subjected to the highly inhomogeneous external ic field due to the cylindrical permanent , which is consistent with the ex