Getter-Activated Cryogenic Thermal Switch

A cryogenic thermal switch has been designed, assembled, and tested over a range of temperatures. The switch has no moving parts and has a thermal resistance which can vary about a factor of 3000 on demand by the actuation of a heater. The switch resistance can be varied continuously between “on” and “off” values. This device is a gas-gap heat switch filled and evacuated by a heater-activated getter. The switch contains two end pieces constructed from OFHC copper, separated by a thin gap which is filled with helium gas from the getter. The temperature of the getter controls the pressure of the gas in the switch. A thermal model of the device was set up to predict its performance for various temperatures and gas pressures. Tests down to liquid-helium temperatures verified the predicted resistance ratios between “off” and “on”.