Vibrational characteristics of a superconducting magnetic bearing employed for a prototype polarization modulator

We present the vibrational characteristics of a levitating rotor in a superconducting magnetic bearing (SMB) system operating at below 10 K. We develop a polarization modulator that requires a continuously rotating optical element, called half-wave plate (HWP), for a cosmic microwave background pola...

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Bibliographic Details
Published in:Journal of physics. Conference series 2017-07, Vol.871 (1), p.12091
Main Authors: Sakurai, Yuki, Matsumura, Tomotake, Sugai, Hajime, Katayama, Nobuhiko, Ohsaki, Hiroyuki, Terao, Yutaka, Terachi, Yusuke, Kataza, Hirokazu, Utsunomiya, Shin, Yamamoto, Ryo
Format: Article
Language:English
Subjects:
Cosmic microwave background
Cryogenic temperature
Damping
Hall effect
High temperature superconductors
Magnetic bearings
Permanent magnets
Physics
Polarization
Prototypes
Rotors
Space missions
Spring constant
Superconductivity
Vibration measurement
Wave plates
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Summary:We present the vibrational characteristics of a levitating rotor in a superconducting magnetic bearing (SMB) system operating at below 10 K. We develop a polarization modulator that requires a continuously rotating optical element, called half-wave plate (HWP), for a cosmic microwave background polarization experiment. The HWP has to operate at the temperature below 10 K, and thus an SMB provides a smooth rotation of the HWP at the cryogenic temperature of about 10 K with minimal heat dissipation. In order to understand the potential interference to the cosmological observations due to the vibration of the HWP, it is essential to characterize the vibrational properties of the levitating rotor of the SMB. We constructed a prototype model that consists of an SMB with an array of high temperature superconductors, YBCO, and a permanent magnet ring, NdFeB. The rotor position is monitored by a laser displacement gauge, and a cryogenic Hall sensor via the magnetic field. In this presentation, we present the measurement results of the vibration characteristics using our prototype SMB system. We characterize the vibrational properties as the spring constant and the damping, and discuss the projected performance of this technology toward the use in future space missions.
ISSN:1742-6588
1742-6596
DOI:10.1088/1742-6596/871/1/012091