Thermal design utilizing radiative cooling for the payload module of LiteBIRD
Takashi Hasebe, Shingo Kashima, Satoru Uozumi, H. Ishino, Shin Utsunomiya, Hirofumi Noda, Kazuhisa Mitsuda, Yutaro Sekímoto, Tadayasu Dotani, T. Matsumura, Hajime Sugai, Masahiro Tsujimoto, Hiroaki Imada, M. Hazumi · Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave · 2018
The conceptual thermal design of the payload module (PLM) of LiteBIRD utilizing radiative cooling is studied. The thermal environment and structure design of the PLM strongly depend on the precession angle α of the spacecraft. In this study, the geometrical models of the PLM that consist of the sunshield, three layers of Vgrooves, and 5 K shield were designed in the cases of α = 45° , 30° , and 5° . The mission instruments of LiteBIRD are cooled down below 5 K. Therefore, heat transfers down to the 5 K cryogenic part were estimated in each case of α. The radiative heat transfers were calculated by using geometrical models of the PLM. The conductive heat transfers and the active cooling with cryocoolers were considered. We also studied the case that the inner surface of the V-groove is coated by a high-emissivity material.