OBTAINING ULTRALOW TEMPERATURES BY DILUTION OF <sup>3</sup>He INTO <sup>4</sup>He

Frossati, G.

doi:10.1051/jphyscol:19786604

“…From Equations (17) and (18), the maximum temperature ratio (corresponding to zero heat transfer in the mixing chamber) is T 1 /T m ¼ 2.80. For a value of T m ¼ 0.040 K, the largest value for T 1 for a positive refrigeration effect is 0.112 K, which yields a maximum temperature difference at the cold end of the exchanger of (T 1 À T m ) ¼ 0.072 K. Heat exchangers with large surface areas per unit volume have been developed using sintered metal elements within the flow passages [51].…”

Section: Dilution Refrigeratormentioning

confidence: 99%

Cryogenic Technology

Barron

¹

2000

Ullmann's Encyclopedia of Industrial Chemistry

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The article contains sections titled: 1. Introduction 2. Uses 3. Liquefaction Systems 3.1. Joule ‐ Thomson Effect 3.2. Basic Linde ‐ Hampson System 3.3. Precooled Linde ‐ Hampson System 3.4. Linde Dual‐Pressure System 3.5. Claude Liquefier 3.6. Liquefaction Systems for Natural Gas 3.7. Collins Helium‐Liquefaction System 3.8. Miniature Liquefaction Systems 3.9. Comparison of Liquefaction Systems 4. Cryogenic Refrigeration Systems 4.1. Thermodynamically Ideal Refrigerator 4.2. Joule ‐ Thomson Refrigerators 4.3. CVI Cold‐Gas Refrigerator 4.4. Stirling Refrigerator 4.5. Vuilleumier Refrigerator 4.6. Solvay Refrigerator 4.7. Gifford ‐ McMahon Refrigerator 4.8. Magnetic Refrigerators 4.9. Dilution Refrigerator 5. Components of Liquefiers and Cryocoolers 5.1. Cryogenic Heat Exchangers 5.1.1. Types of Cryogenic Heat Exchangers 5.1.2. Heat Exchangers for Dilution Refrigerators 5.1.3. Heat Exchanger Design Problems 5.1.4. Regenerators 5.2. Compressors 5.3. Expanders 6. Low‐Temperature Separation Systems 6.1. Minimum Work of Separation 6.2. Properties of Mixtures 6.3. Flash Calculation 6.4. Principles of Cryogenic Rectification 6.5. Linde Single‐Column System 6.6. Linde Double‐Column System 6.7. Heylandt System 6.8. Argon Separation 6.9. Neon Separation 6.10. Physical Adsorption

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“…For Pt K = 0.029sK. The nuclei will absorb energy from the electrons which are at a temperature We, at a rate (~-nA(B~B~) (T~-T.) (18) gtok T.…”

Section: Aq = Cb Dt = Tzotimentioning

confidence: 99%

“…Instead of pairing in the singlet state like the electrons, that is, with opposite spins so that the total spin S and angular momentum l are zero, 3He atoms pair in a spin triplet state with a total angular momentum l = 1. The wave functions describing superfluid 3He has thus many components (18), depending on the spin and angular momentum quantum numbers ms and mr, which can take the values +1 and zero. There are thus several possible phases unlike electrons or 4He which have only one (see Leggett's lectures).…”

Section: Introductionmentioning

confidence: 99%

Experimental techniques: Methods for cooling below 300 mK

Frossati

¹

1992

Self Cite

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There are at present three methods for cooling samples to temperatures below 300 mK: dilution, Pomeranchuk, and nuclear refrigeration. We give the basic principles of these methods with more details concerning dilutions refrigerators. This should allow the construction of a simple all plastic refrigerator for temperatures lower than 15 mK, or an even simpler Pomeranchuk cell. The source of heat leaks and other important points for reaching temperatures in the microkelvin range with nuclear refrigerators are given in the lecture by F. Pobell.

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“…Technical details about the design and construction of the 1 K pot, the still, the continuous counter flow heat exchangers (HE), and the mixing chamber (MC) can be found in the literature. 5,6,11,12 This system has very large cooling power: Q 120 mK = 1300 µW, Q 30 mK = 100 µW, and Q 10 mK = 10 µW at the circulation rate of 1.5 mmole/s. Without the copper nuclear stage we reached a base temperature of 3.15 mK.…”

Section: Dilution Refrigerator and Magnetmentioning

confidence: 99%

“…Some of the major achievements in dilution refrigeration and nuclear cooling can be found in the literature. [5][6][7][8][9][10][11][12] In this paper, we describe the construction and performance of a new nuclear demagnetization refrigerator which was designed for experimental work on condensed matter at microkelvin temperatures.…”

Section: Introductionmentioning

confidence: 99%

The Vienna Nuclear Demagnetization Refrigerator

Nguyen

¹

,

Sidorenko

²

,

Mûller

³

et al. 2012

J. Phys.: Conf. Ser.

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Abstract.A new nuclear demagnetization system coupled to a powerful dilution refrigerator and a vector magnet was successfully built and operated. Our aim was to construct a versatile, modular cryostat, with a large experimental space providing an excellent platform for various types of ultralow temperature measurements. A powerful dilution unit allows us to cool the mixing chamber down to 3 mK and to precool a massive copper (~90 mol) nuclear stage in a field of 9 T to 8 mK in 100 h. After demagnetization the lowest temperature of the copper stage measured by a Pt thermometer was 50.9 µK in a field of 20 mT. The cryostat is integrated with a 8 T -4 T vector magnet system. The refrigerator is provided with a 50 mm central clear shot tube allowing the insertion of a top-loading probe to cool down samples for measurements inside the vector magnet bore in a reasonably short time of about 4 hours. The system will be used to study quantum critical behavior of heavy fermion compounds.

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OBTAINING ULTRALOW TEMPERATURES BY DILUTION OF ³He INTO ⁴He

Cited by 38 publications

References 2 publications

Cryogenic Technology

Cryogenic Technology

Experimental techniques: Methods for cooling below 300 mK

The Vienna Nuclear Demagnetization Refrigerator

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OBTAINING ULTRALOW TEMPERATURES BY DILUTION OF 3He INTO 4He

Cited by 38 publications

References 2 publications

Cryogenic Technology

Cryogenic Technology

Experimental techniques: Methods for cooling below 300 mK

The Vienna Nuclear Demagnetization Refrigerator

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Product

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OBTAINING ULTRALOW TEMPERATURES BY DILUTION OF ³He INTO ⁴He