Cryostat for transporting cooled equipment at a cryogenic temperature

Abstract

A cryostat for transporting cooled equipment at an upper cryogenic temperature, the cryostat being arranged to cool the cooled equipment by a working cryogen which boils at a lower cryogenic temperature, comprising a vacuum container surrounding the cooled equipment and defining a nominally evacuated layer between the vacuum container and the cooled equipment. Means are provided to reduce contamination of the nominally evacuated layer by a vacuum contaminant which is present in gaseous form within the evacuated layer at the upper cryogenic temperature, but which is retained in liquid or solid form at the lower cryogenic temperature.

Description

technical field [0001] The invention relates to a cryostat Background technique [0002] As is known in the art, a cryogenic cooling device, such as a superconducting magnet structure for a magnetic resonance imaging (MRI) system, is typically delivered in a cryostat at least partially filled with a working cryogen. During delivery, the refrigerant boils, thereby maintaining the cooling unit at the boiling point of the operating refrigerant. [0003] During transport, the rate at which the cooling unit heats up depends on the heat flow into the unit. This is determined by three main reasons. First, radiant heat is emitted from a relatively warm surface onto adjacent surfaces of the cooler. A typical example of this is the relatively warm outer vacuum chamber radiating heat onto the cryogen vessel containing the cooling device. Second, heat can be conducted through the mechanical support structure that holds the cooling device in place, or the mechanical support structure...

AI Technical Summary

Problems solved by technology

Some frozen vacuum contaminants will return to a gaseous state, reducing the quality of the vacuum

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