| 摘要 |
The piston's (3) central radial flange (35), tightly gripped by the two similar halves of an outer, non-magnetic, finned casing (1,7), projects, on one side (37), to support the warm zone (51) of the refrigerating probe or finger (5). Compression chambers (4,4') at either piston end are enclosed by cylinders (2,2') carrying peripheral permanent magnets (21,21'), and stabilised axially by helical springs (42,43). The magnet/cylinder assemblies, enclosed in a sealed chamber, oscillate in the alternating field provided by embedded coils (12,12'). Piston passages (61,62) connect working fluid, e.g. helium in the cylinders with the finger (5), which, enclosed within a Dewar flask (58), contains a regenerator (56) resonating on a spring (52) in the warm end (51). The item to be cooled (9) is fixed to the cold end (53).
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