Prior to circulating the 3He/4He mixture, the KelvinoxVT is cooled to below 2 K by the variable temperature insert exchanging stage and the appropriate volume of exchange gas. This heat exchanger is a continuous-flow type that is fed through a needle valve and capillary from the helium bath, located well above the horizontal beamline. Once the dilution refrigerator has been cooled down to below 2 K, the mixture is then condensed and circulated as in a conventional dilution refrigerator. Once circulating, the returning 3He is condensed by heat exchange to the VTI (at ~1.5 K) providing a 'pot-less' condensing stage.
This compact system can be cooled down to base temperature in around three hours from loading. Temperature control can be achieved when circulating up to a temperature of approximately 3 K. The VTI temperature control can be used for higher temperatures up to 300 K.
This compact system can be cooled from room to base temperature in about 6 hours.
