【作者】 宋宏海；

【导师】 王家素；

【作者基本信息】 西南交通大学 ， 电工理论与新技术， 2004， 硕士

【摘要】 本文通过实验测试和理论计算研究了永磁导轨上方高温超导块材及其组合的悬浮和导向性能。原二维Prigozhin模型假设高温超导体各向同性，临界电流密度为常量。对称外场中计算结果和实验结果定性吻合，但是前者几乎是后者两倍多；非对称外场中计算结果和实验结果定性和定量差别很大。本文首先用指数模型和Kim模型代替Bean模型考虑外场大小对临界电流密度的影响。指数模型的指数关系J_c(B)由实验曲线拟和而得，而Kim模型的可调参数较多，所以前者更适合数值计算。竖直截面电流分布说明磁化电流集中在超导体表面，但是非对称外场中悬浮力计算结果和实验结果依然不吻合。 接着本文考虑了高温超导体YBCO层状结构带来的各向异性。其一采用了Yang等提出的近似余弦角度关系和各向异性GL方程角度关系描述外场方向对临界电流密度的影响。其二通过调节截面分层方式近似描述临界电流密度各向异性。此外，在探讨超导块材三维电流分布的基础上，本文提出了“准”三维模型，该模型考虑二维模型计算块材和实际块材的维数区别，假设存在虚拟端面，使得计算结果和实验结果在对称和非对称外场中取得定量吻合。最后本文还探索了新磁通涡旋现象，比如涡旋锁定、几何锁定等，以及新电磁特性，进一步地改善了计算结果。本文深入研究了高温超导体各向异性，为高温超导磁悬浮系统设计提供了一定科学依据。更多还原

【Abstract】 Both levitation and guidance performance of a single bulk and bulk array have been studied in this paper, from the points of both experimental measurements and theoretical calculations. The high temperature superconductor (HTS) was assumed to be isotropic and the critical current density is constant independent of the applied magnetic field in the Two Dimensional Progozhin model. Its calculated levitation force in symmetrical applied field qualitatively agreed with the experimental levitation force. However the former were roughly twice more than the latter. In unsymmetrical applied fields, there were both qualitative and quantitative differences between the calculated and experiemental results. Kim model and Exponential model were employed in terms of the magnitude dependence of the critical current density on the applied magnetic field. The Kim model has several parameters to be determined, which is not fit for the numerical caculations. However, the exponential relationship in the Expoential model was fitted from the measured JC(B) curve. So the Exponential model was preferred in the calculations, and its calculated current distributions upon the vertical cross section indicate that the magnetization currents flowing in the penetration part close to the superconductor bulk’s surface. But the calculated levitation force had no significant improvement in the unsymmetrical applied fields.Subsequently, the anisotropy resulting from the layer structure of YBCO superconductor was taken into account in the computation from two sides. One is to respectively consider the angle dependence of the critical current density on the applied field using the proximate cosine angle dependence and the anisotropic GL fuction angle dependence. The other side is to approximately describe the anisotropy ratio of critical current density through adjusting the layer thickness upon the vertical cross section. Furthurmore, based on the prelimary analysis of the Tripple Dimensional distribution of the magnetization current, the quasi Tripple Dimensional model was proposed, considering the differerace between the calculated bulk in Two Demensioal model and the practical sample in the experiments. Two end sections are supposed in the quasi Tripple Dimensional model, and the qualitative agreement between calculated and experimental results can be obtained. Furthuremore the newphenomenon in terms of vortex was studied, such as vortex locking, geometrical locking resulting in new magnetic interactions. The calculated results were improved northerly. This work will do some contributions to the anisotropy theory of HTS bulk and the present HTS Maglev system design.更多还原