Thermal contacts through mechanical moving parts in low thermal budget optical cryogenic assemblies

Abstract

Ball bearings or mechanical reductors constitute thermal impedances that can reach the known poor level of thermal radiative exchange at low temperatures, 6 × 10 4 Km −2 W −1. This can induce unacceptable hoop stresses when cooling down high heat capacity components or create thermal heterogeneities on scientific experiments and superconducting devices which are supposed to be cold and isothermic. Soft metallic contacts afford good thermal contacts but cause higher mechanical torque and then increase the heat flux through the contact line. The developments described here were made on one of the four Infrared Space Observatory experiments.