Nuclear refrigeration of copper

Berglund, P.; Ehnholm, Gösta; Gylling, R.G.; Lounasmaa, O. V.; Søvik, R.P.

doi:10.1016/0011-2275(72)90043-4

Cited by 26 publications

(7 citation statements)

References 7 publications

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“…10 It has a two-stage pulse tube refrigerator with a base temperature of 3 K for the second stage. For condensation of 3 He- 4 He mixture, the system employs a 2 bar compressor, which can be switched off during continuous circulation. The dilution unit cools down to 7 mK and provides 550 μW of cooling power at 100 mK.…”

Section: The Cryogen-free Demagnetization Refrigeratormentioning

confidence: 99%

“…In this first experiment, only an oscillating fork was installed inside the cell. Approximately 0.6 mol of 3 He of 200 ppm 4 He purity was condensed to the cell. This resulted in a partially filled chamber with a free liquid-vapor interface.…”

Section: The Cryogen-free Demagnetization Refrigeratormentioning

confidence: 99%

“…As a consequence, most of the modern sub-mK nuclear demagnetization refrigerators employ Cu for the nuclear cooling stage. [4][5][6][7][8][9] However, Cu stage is more sensitive to external heat loads because of the very demanding precooling conditions to fully polarize the nuclear spins in copper. Furthermore, due to the high electrical conductivity, a good-quality Cu nuclear stage is extremely prone to eddy current heating.…”

Section: Introductionmentioning

confidence: 99%

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

Todoshchenko

Kaikkonen

Blaauwgeers

et al. 2014

Review of Scientific Instruments

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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 3 He. 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 3 He. We show that the fork oscillator can be considered as self-calibrating in superfluid 3 He at the crossover point from hydrodynamic into ballistic quasiparticle regime.

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Section: The Cryogen-free Demagnetization Refrigeratormentioning

confidence: 99%

Section: The Cryogen-free Demagnetization Refrigeratormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Todoshchenko

Kaikkonen

Blaauwgeers

et al. 2014

Review of Scientific Instruments

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“…When nuclear demagnetization was first applied using copper, it was believed that fine geometry of the refrigerant was essential to reduce eddy current heating by demagnetization. The first cryostat in which copper nuclear demagnetization and the 3 He- 4 He dilution refrigerator were combined was constructed by Bergland et al [17] in 1972. Their nuclear stage was made of 70,000 insulated 99.999%-pure copper wires with a diameter of 0.05 mm.…”

Section: Copper Nuclear Stagementioning

confidence: 99%

Nuclear demagnetization for ultra-low temperatures

Abe

Matsumoto

2014

Cryogenics

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Nuclear demagnetization is one of the most successful methods of cooling an appreciable amount of matter to the lowest temperatures. The principle of nuclear demagnetization is the same as that of the adiabatic demagnetization of a paramagnetic salt; however, there is a significant difference in practice. This article focuses on nuclear demagnetization refrigeration used in experiments at millikelvin and much lower temperatures. After a brief overview of the basic principle and methods, typical requirements of the refrigerants are described from the view point of experiments. The heat switch and thermometry used in nuclear demagnetization experiments are also discussed.

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“…Additionally, copper is more available, easier to handle, and it provides better thermal conductivity when compared with PrNi 5 . As a consequence, most of the modern sub-mK nuclear demagnetization refrigerators employ Cu for the nuclear cooling stage [4][5][6][7][8][9] . However, Cu stage is more sensitive to external heat loads because of the very demanding precooling conditions to fully polarize the nuclear spins in copper.…”

Section: Introductionmentioning

confidence: 99%

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

Todoshchenko,

Kaikkonen,

Blaauwgeers

et al. 2014

Preprint

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Nuclear refrigeration of copper

Cited by 26 publications

References 7 publications

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

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

Nuclear demagnetization for ultra-low temperatures

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

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