Selected Publications

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

Todoshchenko, I., Kaikkonen, J.-P., Blaauwgeers, R., Hakonen, P. J. and Savin, A.

We demonstrate successful “dry” refrigeration of quantum fluids down to = 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 3He. 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 = 4.4 nW obtained in field of 35 mT. For thermometry, we employed a quartz tuning fork immersed into liquid 3He. We show that the fork oscillator can be considered as self-calibrating in superfluid 3He at the crossover point from hydrodynamic into ballistic quasiparticle regime.

Review of Scientific Instruments, 85, 085106 (2014)

doi: 10.1063/1.4891619