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 ringshaped 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.
AbsiracCHybrid superconducting magnetic bearing(SMB), using YBCO high temperature superconductors(€ITS) coupled with permanent magnets, has been implemented into a flywheel energy storage(FES) system prototype. The hybrid S M B design uses permanent magnets to levitate the rotor weighing 19 kg and superconductors to stabilize the inherently unstable magnet-magnet interactions. The SMB bearings are brought into action under convenient field-cooled conditions. Spin-down performance of the constructed FES prototype was tested under a moderate vacuum.
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