Development and testing of an advanced cryogenic thermal switch and cryogenic thermal switch test bed

Abstract This paper describes development details and performance results of a high performance, highly reliable cryogenic thermal switch (CTSW), US Patent Number 6,276,144 B1, and cryogenic thermal switch test bed. The principle application for this device is to couple redundant cryocoolers to a cryogenic component with minimal parasitic heat leak from the non-operating cryocooler. Additional applications for the CTSW are also considered. Constructed of only three parts and weighing less than 80 g, the device operates based on differential thermal expansion. The design is readily scalable and operates with a variety of material selections. The device has demonstrated an “On” conductance greater than 3.5 W/K, an “Off” resistance of greater than 2300 K/W and a switching ratio of more than 5000, with no performance degradation due to thermal cycling. A cryogenic thermal switch test bed has been designed to demonstrate the system benefits of the device for systems utilizing redundant cryocoolers. This test bed utilizes two CTSWs in conjunction with two tactical cryocoolers to quantitatively measure the power savings and/or the operating temperature benefits of the CTSW. Additionally, the test bed may be used to life test and thermally cycle the CTSW.