Cold Finger Helium Reliquefier


Quantum Cold Finger Helium Reliquefiers are devices which can liquefy or re-liquefy gases at a distance from the main cooler. The flexible interconnection allows isolating the mechanical vibration and magnetic noise from the cold head from the object being cooled. Quantum custom builds these flexible cryogenic lines for cooling physics samples, creating liquid gas targets.

Principle of Operation

A small cold finger is inserted into the top of the device to be cooled. Boiling of liquid helium in the device continues at the usual rate, but as the cold gas rises it is recondensed on the surface of the cold finger and falls back as liquid. Thus, the net boiloff is reduced to zero.

The QUANTUMCOOLER cold finger is designed for field retrofit installation. It may be inserted into any system even while the magnet is at full field, via the large port which is typically used for the magnet current leads. It is easily removed in minutes.

In the specific case of whole body MRI magnets there are heat shields cooled either by liquid nitrogen or active cold head cooling. The QUANTUMCOOLER cold finger neither affects nor replaces this shield cooling. Magnets with active cold head shield cooling can expect to have their helium boiloff reduced or totally eliminated. MRIs with liquid nitrogen cooling will have the helium boiloff reduced to a fraction of its initial value.

The operation of the MRI is not affected by the coldfinger. Because of its nonmagnetic, zero vibration, construction it is also recommended for spectroscopy applications. The helium of the MRI stays in the MRI and is totally separate from the closed-circuit helium used in the QUANTUMCOOLER. A redundant circuit maintains a small positive pressure (typically 0.07 bar = 1 psig) to prevent any possible contamination of the MRI.

Schematic of the installation

Cross section view of top of MRI showing cold helium gas condensing on coldfinger and falling as liquid.

Quantum Recondenser System with flexible transfer line

a. MRI LHe reservoir
b. Flexible QUANTUM INTERCONNECT transfer line
c. QUANTUM RECONDENSER cryostat - can be located
inside or outside of shielded room
d. Electronic display with one button start/stop operation
e. Closed-cycle refrigeration (helium) compressors
f. Patient area or shielded room
g. MRI Superconducting Magnet

SERVICE INTERVAL: 10,000 hours. An inexpensive replacement of consumables is required.