Thermal analysis of a prototype cryogenic polarization modulator for use in a space-borne CMB polarization experiment

T. Iida, Y. Sakurai, T. Matsumura, H. Sugai, H. Imada, H. Kataza, H. Ohsaki, M. Hazumi, N. Katayama, R. Yamamoto, S. Utsunomiya, Y. Terao

Research output: Contribution to journalConference articlepeer-review

2 Citations (Scopus)


We report a thermal analysis of a polarization modulator unit (PMU) for use in a space-borne cosmic microwave background (CMB) project. A measurement of the CMB polarization allows us to probe the physics of early universe, and that is the best method to test the cosmic inflation experimentally. One of the key instruments for this science is to use a halfwave plate (HWP) based polarization modulator. The HWP is required to rotate continuously at about 1 Hz below 10 K to minimize its own thermal emission to a detector system. The rotating HWP system at the cryogenic environment can be realized by using a superconducting magnetic bearing (SMB) without significant heat dissipation by mechanical friction. While the SMB achieves the smooth rotation due to the contactless bearing, an estimation of a levitating HWP temperature becomes a challenge. We manufactured a one-eighth scale prototype model of PMU and built a thermal model. We verified our thermal model with the experimental data. We forecasted the projected thermal performance of PMU for a full-scale model based on the thermal model. From this analysis, we discuss the design requirement toward constructing the full-scale model for use in a space environment such as a future CMB satellite mission, LiteBIRD.

Original languageEnglish
Article number012011
JournalIOP Conference Series: Materials Science and Engineering
Issue number1
Publication statusPublished - Dec 30 2017
Externally publishedYes
Event2017 Cryogenic Engineering Conference, CEC 2017 - Madison, United States
Duration: Jul 9 2017Jul 13 2017

ASJC Scopus subject areas

  • General Materials Science
  • General Engineering


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