| 摘要 |
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 pulse tube refrigerator PTR arrangement within a cryogenic apparatus, wherein a PTR is operable within an insertion sock associated with a housing of the cryogenic apparatus for the placement of the PTR such that a first end is exposed to room temperature and a second end is associated with a cryogenic fluid, wherein the tubes of the PTR are surrounded by an insulating 2s sleeve. This configuration has been shown to reduce convection and problems associated therewith. |
