A calorimeter for multilayer insulation (MLI) performance measurements at variable temperature

• Innovative instrument for measuring the thermal conductivity of MLI is described.
• Calorimeter can have independently controlled the boundary temperatures.
• Two Gifford-McMahon cryocoolers control the boundary temperatures.
• The heat transfer rate is measured using a calibrated heat load support rod.

Here we describe a concentric cylindrical calorimeter with radiation guards developed to measure the thermal performance of multilayer insulation (MLI) for low temperature applications. One unique feature of this calorimeter is its ability to independently control the boundary temperatures between room temperature and about 15 K using two single-stage Gifford–McMahon cryocoolers. Also, unlike the existing calorimeters that use the evaporation rate of a liquid cryogen to measure the heat load, in the present system the total heat transfer through the MLI is measured by recording the temperature difference across a calibrated heat load support rod that connects the cold inner cylinder to the lower temperature cryocooler. This design allows the continuous mapping of MLI performance over a much wider temperature range with independently controlled boundary conditions. The calorimeter is also suitable for performing a variety of radiation heat transfer experiments including the determination of the temperature dependence of the total emissivity.