Journal of Applied Science and Engineering

Published by Tamkang University Press

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1.60

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W. C. Chan This email address is being protected from spambots. You need JavaScript enabled to view it.1,Y. P. Yang1 and C. H.Chiang1

1Physics Department, Tamkang University, Tamsui, Taiwan 251, R.O.C.


 

Received: December 26, 2006
Accepted: June 30, 2007
Publication Date: June 1, 2008

Download Citation: ||https://doi.org/10.6180/jase.2008.11.2.03  


ABSTRACT


A modified close cycle helium gas cryogenic system was used to measure the flux drag torque acting on a free spinning disk magnet by a single grain YBCO superconductor. It was found that at low spinning speed ( less than 8 Hz ) and constant levitation height, the flux drag torque decreased with temperature which behavior is roughly similar to the temperature dependence of the reciprocal of critical current density for a single grain superconductor.


Keywords: Critical Current Density, Flux Pinning and Creep, Superconducting Bearings


REFERENCES


  1. [1] Bornemann, H. J., Ritter, T.,.Urban, C., Zaitsev, O., Weber, K. and Rietschel, H., “Low Friction in a Flywheel System with Passive Superconducting Magnetic Bearings,” Appl. Supercond., Vol. 2, pp. 439447 (1994).
  2. [2] Hull, J. R., “Superconducting Bearings,” Supercond. Sci. Technol., Vol. 13, pp. R115 (2000).
  3. [3] Cansiz, A., Campbell, A. M. and Coombs, T. A., “An Evershed Type Superconducting Flywheel Bearing,” Physica C, Vol. 390, pp. 305310 (2003).
  4. [4] Day, A. C., Hull, J. R., Strasik, M., Johnson, P. E., McCrary, K. E., Edward, J., Mittleider, J. A., Schindler, J. R., Hawkins, R. A. and Yoder, M. L., “Temperature and Frequency Effects in a High-Performance Superconducting Bearing,” Appl. supercond., Vol. 13, pp. 21792184 (2003).
  5. [5] Chan, W. C. and Chung, C. J., “Magnetic Flux-Drag Forces for High-Tc Superconductors,” J. Appl. Phys., Vol. 73, pp. 50955097 (1993).
  6. [6] Moon, F. C. and Chang, P. Z., “High-Speed Rotation of Magnets on High Tc Superconducting Bearings,” Appl. Phys. Lett., Vol. 56, pp. 397399 (1990).
  7. [7] Weeks, D. E., “Rotational Dynamics of Passive High Tc Superconducting Bearings,” J. Appl. Phys., Vol. 70, pp. 18201825 (1991).
  8. [8] Weinberger, B. R., Lynds, L., Hull J. R. and Balachandran, U., “Low Friction in High Temperature Superconductor Bearings,” Appl. Phys. Lett., Vol. 59, pp. 11321134 (1991).
  9. [9] Terentiev, A. N., Kutukova, E. O., Kuznetsov, A. A. and Mozhaev, A. P. “Spinning Rate Decay of Levitated High-Tc Superconductors in Rotational Magnetic Field,” Physica C, Vol. 193, pp. 110116 (1992).
  10. [10] Chen, I. G., Hsu, J. C., Janm, G., Kuo, C. C., Liu, H. J. and Wu, M. K., “Magnetic Levitation Force of Single Grained YBCO Material,” Chinese J. Phys., Vol. 36, pp. 420427 (1998).
  11. [11] Bean, C. P., “Rotational Hysteresis Loss in High-Field Superconductors,” J. Appl. Phys., Vol. 41, pp. 2482 2483 (1970).
  12. [12] Hull, J. R., Mulcahy, T. M., Uherka, K. L., Erck, R. A. and Abboud, R. G., “Flywheel Energy Storage Using Superconducting Magnetic Bearings,” Appl. Supercond., Vol. 2, pp. 449455 (1994).
  13. [13] Chan, W. C., Jwo, D. S. and Lee, J. J., “Bean’s Model and Magnetic Flux-Drag Torques for High-Tc Superconductors,” Physica C, Vol. 252, pp. 203207 (1995).
  14. [14] Uspenskaya, L. S., Vlasko-Vlasov, V. K., Nikitenko, V. I. and Johansen, T. H., “Magneto-Optical Studies of Magnetization of Melt-Processed YBCO,” Phys. Rev. B, Vol. 56, pp. 1197911988 (1997).