Estimation of the Heat Dissipation and the Rotor Temperature of Superconducting Magnetic Bearing Below 10 K
Estimation of the Heat Dissipation and the Rotor Temperature of Superconducting Magnetic Bearing Below 10 K
复制标题
10 K以下超导磁力轴承的散热量和转子温度估算
DOI：
10.1109/tasc.2017.2672688
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发表时间：
2017
影响因子：
1.8
通讯作者：
and R. Yamamoto
中科院分区：
文献类型：
--
作者：
Y. Sakurai;T. Matsumura;H. Kataza;S. Utsunomiya;and R. Yamamoto
介绍了用于宇宙微波背景极化实验偏振调制器的超导磁轴承(SMB)系统的热特性。SMB系统由环形磁铁和YBCO瓷砖阵列组成。两者的开口直径都约为400毫米。环形磁体由分段磁体阵列形成。该转子磁体的磁场不均匀性是由各磁体的磁场不均匀性和磁段之间的空间间隙引起的。这种不均匀可以作为摩擦源，从而在低于10K的操作中作为热源。我们通过进行自旋向下测量估计了SMB的摩擦散热，并根据悬浮高度的不同预测了磁滞贡献的2-20 mW的散热。我们讨论了磁场不均匀和磁滞损耗之间的自旋下降测量与Bean模型的一致性。我们还讨论了转子磁体在10K左右悬浮时的潜在温升，从而提出了通过与转子的物理接触来估计转子温度的方法。外推温度不经任何修正即可恢复转子温度，误差小于2K。
We present the thermal characteristics of a superconducting magnetic bearing (SMB) system that is designed for a polarization modulator of a cosmic microwave background polarization experiment. The SMB system consists of a ring-shaped magnet and an array of YBCO tiles. Both have an opening diameter of about 400 mm. The ring-shaped magnet is formed by an array of segmented magnets. The magnetic field inhomogeneity of this rotor magnet is originated from the magnetic field inhomogeneity of each magnet and the spatial gap between the segments. This inhomogeneity can contribute as a source of friction, and thus a source of heat in an operation at below 10 K. We estimate the heat dissipation from friction of the SMB by conducting the spin-down measurements, and we projected the heat dissipation of 2-20 mW from the hysteresis contribution depending on the levitation height. We discuss the consistency of the spin-down measurements to Bean's model between the magnetic field inhomogeneity and the hysteresis loss. We also discuss the potential temperature rise of the rotor magnet when it is levitating at the temperature at around 10 K. Thus, we address the means to estimate the rotor temperature by the physical contact to the rotor. The extrapolated temperature recovers the rotor temperature with the difference of less than 2 K without any correction.