A cosmic microwave background radiation polarimeter using superconducting bearings
Hanany, S.
Matsumura, T.
Johnson, B.
Jones, T.
Hull, J.R.
Ma, K.B.
Sch. of Phys. & Astron., Univ. of Minnesota/Twin Cities, Minneapolis, MN, USA;
This paper appears in: Applied Superconductivity, IEEE Transactions on
Publication Date: June 2003
Volume: 13,
Issue: 2, Part 2
On page(s): 2128- 2133
ISSN: 1051-8223
INSPEC Accession Number: 7711370
Digital Object Identifier: 10.1109/TASC.2003.813016
Current Version Published: 2003-07-15
Abstract
Measurements of the polarization of the cosmic microwave background (CMB) radiation are expected to significantly increase our understanding of the early universe. We present a design for a CMB polarimeter in which a cryogenically cooled half wave plate rotates by means of a high-temperature superconducting (HTS) bearing. The design is optimized for implementation in MAXIPOL, a balloon-borne CMB polarimeter. A prototype bearing, consisting of commercially available ring-shaped permanent magnet and an array of YBCO bulk HTS material, has been constructed. We measured the coefficient of friction as a function of several parameters including temperature between 15 and 80 K, rotation frequency between 0.3 and 3.5 Hz, levitation distance between 6 and 10 mm, and ambient pressure between 10-7 and 1 torr. The low rotational drag of the HTS bearing allows rotations for long periods of time with minimal input power and negligible wear and tear thus making this technology suitable for a future satellite mission.
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