wiki:silver_powders
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wiki:silver_powders [2022/02/03 17:36] henri.godfrin@neel.cnrs.fr |
wiki:silver_powders [2022/02/04 13:20] (current) henri.godfrin@neel.cnrs.fr |
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| - | * The Kapitza thermal resistance between 3He or mixtures and sintered silver powders is a particularly important parameter for the design of low temperature heat exchangers. The minimum grain size for mixtures is about 1000Å, because 3He atoms are expelled from small pores, filled essentially by 4He. Note that in the concentrated side of a dilution refrigerator, | + | * The Kapitza thermal resistance between 3He or mixtures and sintered silver powders is a particularly important parameter for the design of low temperature heat exchangers. The minimum grain size for mixtures is about 1000Å, because 3He atoms are expelled from small pores, filled essentially by 4He. Note that in the concentrated side of a dilution refrigerator, |
| - | * The values shown in the graph are typical | + | * The values shown in the graph are typical, but it must be kept in mind that the properties of powders are known to vay, even from batch to batch. Tests must be made to determine the actual Kapitza resistance with any particular powder. Some examples are given in the references below. |
| * Curves for mixtures correspond to the Kapitza resistance measured between sintered silver powder heat exchangers and mixtures, either indirectly through the performance of heat exchangers (G. Frossati), or directly in cells containing helium mixture (H. Godfrin). | * Curves for mixtures correspond to the Kapitza resistance measured between sintered silver powder heat exchangers and mixtures, either indirectly through the performance of heat exchangers (G. Frossati), or directly in cells containing helium mixture (H. Godfrin). | ||
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| * Resistance between Epibond 100A and and mixtures: Anderson et al. (1961) | * Resistance between Epibond 100A and and mixtures: Anderson et al. (1961) | ||
| - | * Resistance between Kapton and and mixtures: B. Hebral, PhD Thesis, Grenoble (1978) | + | * Resistance between Kapton and and mixtures: B. Hébral, PhD Thesis, Grenoble (1978) |
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| * Resistance between 700Å silver powders and pure 3He: measurements by Ahonen, Lounasmaa and Veuro (1978) and H. Godfrin (PhD Thesis, 1981). | * Resistance between 700Å silver powders and pure 3He: measurements by Ahonen, Lounasmaa and Veuro (1978) and H. Godfrin (PhD Thesis, 1981). | ||
wiki/silver_powders.1643909807.txt.gz · Last modified: 2022/02/03 17:36 by henri.godfrin@neel.cnrs.fr
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