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

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© 2014 AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the authors and the American Institute of Physics. The following article appeared in Review of Scientific Instruments, Volume 85, Issue 8 and may be found at http://scitation.aip.org/content/aip/journal/rsi/85/8/10.1063/1.4891619.
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Journal Title

Journal ISSN

Volume Title

School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2014

Major/Subject

Mcode

Degree programme

Language

en

Pages

085106/1-6

Series

Review of Scientific Instruments, Volume 85, Issue 8

Abstract

We demonstrate successful “dry” 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 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 Q = 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.

Description

Keywords

helium, demagnetization, copper, refrigerators, thermometers

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Citation

Todoshchenko, I. & Kaikkonen, J.-P. & Blaauwgeers, R. & Hakonen, Pertti J. & Savin, A. 2014. Dry demagnetization cryostat for sub-millikelvin helium experiments: Refrigeration and thermometry. Review of Scientific Instruments. Volume 85, Issue 8. 085106/1-6. ISSN 0034-6748 (printed). DOI: 10.1063/1.4891619