 Dilution refrigerator still

The dilution refrigerator still is a warmer evaporation stage that preferentially removes helium-3 from the dilute mixture and helps maintain circulation through the dilution unit. Heating it controls the vapor flow returned to the pumping circuit.

The mixing chamber of a dilution refrigerator provides the lowest-temperature cooling, while the still supports the continuous mass flow needed for that process. The still's role is therefore distinct from simply being another cold sample stage.^[ref]