ABSTRACT
This chapter examines the thermal modeling of an experiment. Having a detailed thermal model is important in designing a cryostat and a sorption fridge, because it gives information about the cooling power required by each component. Thermal modeling is useful for estimating the cooldown time for the cryostat, which is of increasing importance for larger experiments. To cool down from room to cryogenic temperature, it is possible to use either a mechanical cooler or liquid cryogens. The use of mechanical coolers is limited to a base temperature of around 3 K, while the use of liquid nitrogen is limited to 77 K. In the absence of convective loading due to high vacuum, main sources of thermal loading on cold stages of a cryostat are conduction through mechanical connections and radiative loading. Conduction on each stage is given principally by conduction through the supports of each stage and conduction through the wires to the various thermometers, heaters and other electrical components.
