Dry demagnetization cryostat for sub-millikelvin helium experiments: Refrigeration and thermometry

作者：Todoshchenko I^*; Kaikkonen J P; Blaauwgeers R; Hakonen P J; Savin A

来源：Review of Scientific Instruments, 2014, 85(8): 085106.

DOI：10.1063/1.4891619

We demonstrate successful %26quot;dry%26quot; refrigeration of quantum fluids down to T = 0.16 mK by using copper nuclear demagnetization stage that is pre-cooled by a pulse-tube-based dilution refrigerator. This type of refrigeration delivers a flexible and simple sub-mK solution to a variety of needs including experiments with superfluid He-3. Our central design principle was to eliminate relative vibrations between the high-field magnet and the nuclear refrigeration stage, which resulted in the minimum heat leak of Q = 4.4 nW obtained in field of 35 mT. For thermometry, we employed a quartz tuning fork immersed into liquid He-3. We show that the fork oscillator can be considered as self-calibrating in superfluid He-3 at the crossover point from hydrodynamic into ballistic quasiparticle regime.

• 出版日期2014-8