高溫超導體YBCO在不同溫度下磁摩擦力的量測

The measurement of the Magnetic Frictional Force of high Tc superconductor YBCO during different temperature .

楊湧評(Yung-Pin Yang)

指導教授 ： 陳偉正

淡江大學/理學院/物理學系碩士班/碩士(2005年)

https://doi.org/10.6846/TKU.2005.00171

摘要

本論文的主要目的在研究高溫超導體YBCO在不同溫度下，探討在超導體上的永久磁鐵轉動，而得到不同溫度下旋轉頻率與時間的關係。經由探討所得到的數據我們發現在不考慮轉速較高的地方出現的共振所造成部分旋轉能量的轉移而影響磁鐵旋轉頻率遞減的因素有空氣阻力、渦漩電流與磁摩擦力;其中空氣阻力與渦漩電流所造成的旋轉能量損耗接與旋轉頻率成正比，而磁摩擦力與與溫度有關，溫度愈高磁通子進入超導體的數量愈多而磁摩擦力也就愈大。

關鍵字

YBCO ； 磁摩擦力 ； 磁通子

並列摘要

The main objective of this project is to study the behavior of rotation frequency of a permanent magnet levitates above a high-temperature superconductor YBCO versus time under different temperature .There are several factors to slow down the rotation . Such as resonances at high rotation frequency, which can lead to partly energy transmit and decrease the frequency of rotation . For low speed rotation we have air drag on the magnet , eddy current inside the magnet and magnetic frictional force come from the superconductor . It was found that the lost of energy caused by Air drag and Eddy current is directly proportional to the rotation frequency. From our measurements, we found that the magnetic frictional force is a function of temperature . When temperature increases, the number of magnetic fluxoids entering the superconductor increases and this causing the magnetic frictional force increases too .

並列關鍵字

YBCO ； magnetic frictional force ； magnetic fluxoids

參考文獻

4. B.R. Weinberger, L. Lynds, J.R. Hull, U. Balachandran(1991)﹒Low friction in high temperature superconductor bearings﹒ Appl. Phys. Lett. Vol.59, No. 9.

5. John R. Hull and Ahmet Cansiz(1999)﹒Vertical and forces between a

6. W.C. Chan, D.S. Jwo, J.J. Lee(1995)﹒Bean's model and magnetic flux-drag torques for high-Tc superconductors﹒

Physica C 252,203-207.

參考文獻