Crowley Kevin D, Dow Peter, Shroyer Jordan E, Groh John C, Dober Bradley, Spisak Jacob, Galitzki Nicholas, Bhandarkar Tanay, Devlin Mark J, Dicker Simon, Gallardo Patricio A, Harrington Kathleen, Iuliano Jeffrey, Johnson Bradley R, Johnson Delwin, Kofman Anna M, Kusaka Akito, Lee Adrian, Limon Michele, Nati Federico, Orlowski-Scherer John, Page Lyman, Randall Michael, Teply Grant, Tsan Tran, Wollack Edward J, Xu Zhilei, Zhu Ningfeng
Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, New Jersey 08544, USA.
Department of Astronomy, University of Virginia, Charlottesville, Virginia 22904, USA.
Rev Sci Instrum. 2022 May 1;93(5):055106. doi: 10.1063/5.0093857.
We present the design and measured performance of a new carbon fiber strut design that is used in a cryogenically cooled truss for the Simons Observatory small aperture telescope. The truss consists of two aluminum 6061 rings separated by 24 struts. Each strut consists of a central carbon fiber tube fitted with two aluminum end caps. We tested the performance of the strut and truss by (i) cryogenically cycling and destructively pull-testing strut samples, (ii) non-destructively pull-testing the final truss, and (iii) measuring the thermal conductivity of the carbon fiber tubes. We found that the strut strength is limited by the mounting fasteners and the strut end caps, not the epoxy adhesive or the carbon fiber tube. This result is consistent with our numerical predictions. Our thermal measurements suggest that the conductive heat load through the struts (from 4 to 1 K) will be less than 1 mW. This strut design may be a promising candidate for use in other cryogenic support structures.
