'Dry' dilution refrigerator with pulse-tube precooling

摘要

We present construction details and performance measurements of a "dry" dilution refrigerator which is precooled by a pulse-tube refrigerator; no cryo-liquids are required to operate this cryostat. The dilution refrigerator is equipped with a double mixing chamber and reaches a lowest temperature of 4.3 mK. The ~3He throughput of the refrigerator was between 100 and 300 mu mol/s. The total heat leak into the mixing chamber was determined to be 75 nW. For thermometry we had a ~3He melting-curve thermometer at our disposal. Ease of operation and reliability are the characteristics of this type of cryostat.