Cryocoolers 9 pp 727-736 | Cite as

Vibration Reduction in a Set-Up of Two Split Type Stirling Cryocoolers

  • A. P. Rijpma
  • J. F. C. Verberne
  • E. H. R. Witbreuk
  • H. J. M. ter Brake
Chapter

Abstract

At the University of Twente research is in progress on performing magnetocardiography in clinical conditions. For the magnetic measurements High-Tc SQUIDs will be used, which will be cooled by commercial cryocoolers. These coolers consist of separate compressor and displacer modules. The compressors are of the dual opposed pistons type. Since the magnetic measurements are sensitive for movements of magnetic materials as well as for movements of the sensors, it is advantageous to minimise the vibrations caused by the cryocoolers. This is achieved by:

  • Using coolers with dual opposed pistons in the compressor modules.

  • Using two coolers and combining the two displacer modules into one rigid unit and operating them in a dual opposed manner.

The remaining vibrations in the axial direction are about 1 ms−2 for the compressors and 0.2 ms−2 for the displacer unit. In order to reduce these vibrations, the automated control system described in this paper was developed. It uses an adaptive feed-forward algorithm based on the work of Wu1 and Boyle et al.2 and is capable of controlling the vibrations of the two compressors and the displacer unit for multiple harmonics simultaneously. Thus the vibration levels are reduced down to 0.02 ms−2 and 0.01 ms−2 for the compressors and the displacer unit respectively.

Keywords

Control Voltage Automate Control System Control Step Compressor Module Drive Voltage 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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References

  1. 1.
    Wu, Y.A., “Active Vibration control algorithm for Cryocooler”, Adv. Cryo. Eng., Vol. 39, part B, Plenum Press, New York (1994), pp. 1271–1280CrossRefGoogle Scholar
  2. 2.
    Boyle, R., Conners, F., Marketon, J., Arillo, V., James, E., Fink, R., “Non-real time feed forward vibration control system development & test results”, Proc. of the 7-th Int. Cryocooler Conf., Santa Fe (1992), pp. 805–819Google Scholar
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    Van den Bosch, P.J., Ter Brake, H.J.M., Holland, H.J., De Boer, H.A., Verberne, J.F.C., Rogalla, H., “Cryogenic design of a high-Tc SQUID-based heart scanner cooled by small Stirling cryocoolers”, submitted to Cryogenics (1996)Google Scholar
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    Verbeek, D., Heimonds, H., Roos, P., “Performance of the Signaal Usfa Stirling cooling engines”, Proc. of the 7-th Int. Cryocooler Conf., Santa Fe (1992), pp. 728–737Google Scholar
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    Verberne, J.F.C., Bruins, P.C., Van den Bosch, P.J., Ter Brake, H.J.M., “Reduction of the Vibrations generated by Stirling Cryocoolers for cooling a high Tc SQUID magnetometer”, Cryocooler 8, Plenum Press, New York (1995), pp. 465–474Google Scholar

Copyright information

© Springer Science+Business Media New York 1997

Authors and Affiliations

  • A. P. Rijpma
    • 1
  • J. F. C. Verberne
    • 1
  • E. H. R. Witbreuk
    • 1
  • H. J. M. ter Brake
    • 1
  1. 1.Department of Applied PhysicsUniversity of TwenteEnschedeThe Netherlands

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