Test Apparatus Utilizing a Gifford-McMahon Cryocooler to Measure the Thermal Performance of Multilayer Insulation

Abstract A vertical cylindrical calorimeter for measuring the thermal performance of multilayer insulation (MLI) has been developed. Two concentric oxygen-free high-conductivity copper drums are wrapped with sample MLI blankets, and are cooled using a two-stage Gifford-McMahon cryocooler. As the drums are vertically supported, the layer density of the MLI sample is unaffected by gravity. The inner drum is cooled by the 2nd stage of the cooler and is maintained at a temperature of about 6 K. The outer drum is maintained at a temperature of about 65 K by connecting it to the first stage of the cooler. The heat transfer through the blanket is determined by measuring the temperature difference across the stainless steel thermal resistance tube in a heat-flow meter placed between the drum and the cold finger of the cryocooler. The structure of the calorimeter, the calibration procedure, and results for heat flow through the MLI sample are reported.