A progress report is provided on the development of a tiltable continuous miniature dilution refrigerator and associated ³He/⁴He sorption coolers. These systems are currently being developed to provide sub-Kelvin cooling of the bolometer arrays for several ground- and balloon-based experiments which aim to measure the polarization of the Cosmic Microwave Background (QUBIC, LSPE and POLARBEAR-2). The novel tiltable miniaturised system benefits from a lack of external circulation pumps and a mechanically simple design. The condenser of the twin-pumped recirculating diluter is cooled continuously by two ³He/⁴He sorption coolers. The sorption pumps are operated by convective heat switches. The dilution unit features a thermally separated mixing chamber, still and step heat exchangers. The designs and analyses of both the sorption coolers and the diluter are reported; both systems have been manufactured and are presently under test.

Date Published: 22 July 2016
PDF: 6 pages
Proc. SPIE 9912, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II, 991266 (22 July 2016); doi: 10.1117/12.2232609

Published in SPIE Proceedings Vol. 9912:
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II
Ramón Navarro; James H. Burge, Editor(s)