DILUTION REFRIGERATOR FOR SPACE APPLICATIONS WITH A CRYOCOOLER

The development of a new type of dilution cryostat with an open circui t for circulating 3He and 4He makes its use in space possible. If a cr yogenerator is used as precooler to avoid the 4He bath, it is possible to cool the input gas down to 2 K before the dilution unit, using Jou le-Thomson expansion of the mixture at the dilution output. This resul ts in a simple refrigerator with a low power dissipation at 4K and con tinuous operation below 100 mK. The working lifetime of the cryostat i s limited by the quantity of gas. For six years of operation, the gas storage system should contain almost-equal-to 30 kg.