Magnetic field inhomogeneity and torque in high temperature superconducting magnetic bearings
Magnetic field inhomogeneity and torque in high temperature superconducting magnetic bearings
复制标题
高温超导磁力轴承中的磁场不均匀性和扭矩
DOI：
10.1109/tasc.2005.849641
复制
发表时间：
2005
影响因子：
1.8
通讯作者：
T. Jones
中科院分区：
文献类型：
--
作者：
T. Matsumura;S. Hanany;J. Hull;B. Johnson;T. Jones
给出了高温超导轴承中永磁体磁场不均匀性与转子转矩之间关系的实验证据。低于14hz的自旋下降测量用于证明转子在单个旋转周期内的角速度变化与测量的转子磁场空间结构之间的高度相关性。在低于/spl sim/1 Hz的频率下，单个旋转周期内的分数速度变化与旋转平均频率的平方成反比。我们提出，偶极子-偶极子相互作用产生了导致速度变化的扭矩，并且我们表明这种相互作用解释了所观察到的函数对频率的依赖。在高于/spl sim/ 1hz的频率下，测量到的幅度约为旋转平均频率的1%，与实验中的噪声水平一致。结果表明，在每个周期内只需测量一次角度，即可实现转子的弧分精度角编码。
We give experimental evidence for the connection between magnetic field inhomogeneity of a permanent magnet and torque on the rotor in a high temperature superconducting bearing. Spin-down measurements below 14 Hz are used to demonstrate a high degree of correlation between variations in the angular speed of the rotor within a single period of rotation with the measured spatial structure of the magnetic field of the rotor. At frequencies below /spl sim/1 Hz the fractional speed variation within a single period of rotation is inversely proportional to the square of the mean frequency of rotation. We propose that a dipole-dipole interaction gives rise to the torques that lead to speed variations and we show that this interaction explains the observed functional dependence on frequency. At frequencies above /spl sim/1 Hz the measured magnitude is about 1% of the mean frequency of rotation, consistent with the noise level in the experiment. The results imply that arcminute accuracy angular encoding of the rotor can be achieved with a single measurement of angle in each period.