3He gas gap heat switch

Thermal control at 1 K is still demanding for heat switches development. A gas gap heat switch using He-3 gas as the heat-transfer fluid was tested and characterized. The switch is actuated by a sorption pump, whose triggering temperatures were also characterized. Switching times were recorded for different thermalizations of the sorption pump. This paper presents the conductance results of such switch. The temperature scanning of the actuator is also presented. The effect of filling pressure is discussed as well as the thermalization of the sorption pump. About 60 mu W/K OFF-state conductance and 100 mW/K ON-state conductance were obtained at 1.7 K. The actuation temperature is slightly adjustable upon the charging pressure of the working gas. Thermalization of the sorption pump at about 8-10 K is enough for producing an OFF state - it can be comfortably linked to a 4 K stage. Temperatures of 15-20 K at the sorption pump are required for reaching the viscous range for maximum ON conduction. Switching time dependence on the thermalization of the sorption pump is discarded. (C) 2010 Elsevier Ltd. All rights reserved.