Siemens Magnet Technology Ltd.

Florian Steinmeyer

Wolfgang Stautner

The present invention relates to pulse tube refrigerators for recondensing cryogenic liquids. In particular, the present invention relates to the same for magnetic resonance imaging systems. In many cryogenic applications components, e.g. superconducting coils for magnetic resonance imaging (MRI), superconducting transformers, generators, electronics, are cooled by keeping them in contact with a volume of liquified gases (e.g. Helium, Neon, Nitrogen, Argon, Methane . . . ). Any dissipation in the components or heat getting into the system causes the volume to part boil off. To account for the losses, replenishment is required. This service operation is considered to be problematic by many users and great efforts have been made over the years to introduce refrigerators that recondense any lost liquid right back into the bath. The present invention addresses the problems arising from convection which occurs within a pulse tube refrigerator. The invention provides. in a first aspect, a PTR recondenser wherein, the individual tubes of PTR are insulated by a split sleeve around the whole assembly. Preferably, the sleeve is split into two parts. This configuration has been shown to reduce convection and problems associated therewith.

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Oxon, United Kingdom

Florian Steinmeyer