Cryocoolers 11 pp 577-586

Closed-Cycle Cooling of Infrared Detectors to 0.25 K for the Polatron

  • R. S. Bhatia
  • J. J. Bock
  • V. V. Hristov
  • W. C. Jones
  • A. E. Lange
  • J. Leong
  • P. V. Mason
  • B. J. Philhour
  • G. Sirbi
  • S. E. Church
  • B. G. Keating
  • J. Glenn
  • S. T. Chase
  • P. A. R. Ade
  • C. V. Haynes
Chapter

Abstract

We have integrated a 4 K mechanical cryocooler with a three stage 4He/3He/3He sorption refrigerator to achieve cooling down to 0.25 K. The cryocooler consists of two Gifford-MacMahon stages which cool 4He to below its inversion temperature for use in a Joule-Thomson expansion stage. This in turn provides cooling below the critical temperature of 4He. The sorption refrigerator is specified to achieve a heatlift of 3 microwatts at 0.25 K for 12 hours. This cryogenic system will be used for cooling of the bolometric detectors and optics in the Polatron, a ground-based receiver for measurement of the polarisation of the cosmic microwave background radiation at a frequency of 90 GHz. Cooling of sensitive detectors by mechanical cryocoolers can lead to sensitivity degradation due to a combination of microphonic pickup, electromagnetic interference and thermal dissipative heating. We describe the design features incorporated at system level to mitigate these effects. The Polatron also serves as a testbed for technologies to be used on the High Frequency Instrument on the ESA/NASA Planck satellite to measure the temperature anisotropies and polarisation of the cosmic microwave background radiation.

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Copyright information

© Kluwer Academic Publishers 2002

Authors and Affiliations

  • R. S. Bhatia
    • 1
  • J. J. Bock
    • 1
  • V. V. Hristov
    • 1
  • W. C. Jones
    • 1
  • A. E. Lange
    • 1
  • J. Leong
    • 1
  • P. V. Mason
    • 1
  • B. J. Philhour
    • 1
  • G. Sirbi
    • 1
  • S. E. Church
    • 2
  • B. G. Keating
    • 2
  • J. Glenn
    • 3
  • S. T. Chase
    • 4
  • P. A. R. Ade
    • 5
  • C. V. Haynes
    • 5
  1. 1.MS 59-33California Institute of TechnologyPasadenaUSA
  2. 2.Dept. of PhysicsStanford UniversityStanfordUSA
  3. 3.CASA CB-389University of ColoradoBoulderUSA
  4. 4.Chase Research Ltd.SheffieldUK
  5. 5.Astrophysics LaboratoryQMW CollegeLondonUK

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