In order to obtain high regenerative effectiveness, the heat capacity of the regenerator materials must be larger than that of helium as the working gas. For a magnetic regenerator material to be effective in the low temperature range, its transition temperature must be within the range where the helium regenerative operation is performed.
Conventional experimental results indicate that anti-ferromagnetic or ferromagnetic materials with large spin values are suitable. As regenerator materials, sufficient regenerative effectiveness cannot be obtained when only one of these materials or their compounds is packed into the regenerator.
In this study, materials with different heat capacity are arranged in multi-layers in the regenerator to obtain higher regenerative efficiency. The most effective multi-layer regenerator for liquefied helium is analyzed by computer simulation and experimental results. New materials, including heavy rare-earth and antimony (Sb) compounds, are used as the magnetic regenerator materials. Antimony compounds have especially sharp single-phase transition in the low temperature range.
The relation between refrigeration capacity and regenerative effectiveness was discussed when these multi-layer regenerative materials were packed into the second stage of a GM refrigerator.
Multilayer Magnetic Regenerators with an Optimum Structure around 4.2K
Cryocoolers 10 ; Chapter : 73 ; 611-620
2002-01-01
10 pages
Article/Chapter (Book)
Electronic Resource
English
Multilayer Magnetic Regenerators with an Optimum Structure around 4.2 K
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