Development of a contact-less cryogenic rotation mechanism employed for a polarization modulator unit in cosmic microwave background polarization experiments

Yuki Sakurai, Tomotake Matsumura, Nobuhiko Katayama, Teruhito Iida, Kunimoto Komatsu, Hajime Sugai, Hiroyuki Ohsaki, Yutaka Terao, Yukimasa Hirota, Hisashi Enokida

Research output: Contribution to journalConference articlepeer-review

3 Citations (Scopus)

Abstract

We present the design and the performance of a contact-less cryogenic rotation mechanism used in cosmic microwave background (CMB) experiments. A precise measurement of the CMB polarization is possible to verify the cosmic inflation theory that describes the very beginning (10-38 seconds) of the early universe. The polarization modulator, that rotates a half wave plate continuously at the aperture of the telescope, is one of the key instruments in the experiments. In order to reduce noise and systematic uncertainties, the polarization modulator is required a stable rotation with minimal heat dissipation in a cryogenic environment less than 20 K. Thus, we adopted the rotation mechanism that combines completely contact-less bearing and motor, a superconducting magnetic bearing, and a hollow bore synchronous motor. The heat dissipation and the load torque due to the friction can be minimized by avoiding physical contacts. We constructed the prototype of the rotation mechanism and carried out mechanical and thermal performance tests. A continuous rotation test in cryogenic temperature is performed, and it is confirmed that the rotation stability is less than 1% with the rotation frequency between 0.5 Hz and 3.0 Hz. We also conducted a thermal performance test, and obtained the heat dissipation at the rotor of 9.0 mW. We discussed the reduction of heat dissipation using a developed magnetic circuit with improved magnetic field uniformity.

Original languageEnglish
Article number012083
JournalJournal of Physics: Conference Series
Volume1293
Issue number1
DOIs
Publication statusPublished - Oct 15 2019
Externally publishedYes
Event31st International Symposium on Superconductivity, ISS 2018 - Tsukuba, Ibaraki, Japan
Duration: Dec 12 2018Dec 14 2018

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Fingerprint

Dive into the research topics of 'Development of a contact-less cryogenic rotation mechanism employed for a polarization modulator unit in cosmic microwave background polarization experiments'. Together they form a unique fingerprint.

Cite this