Tubular thermal switch for the cryo-free magnet

摘要

When cooling a superconducting magnet for use in a magnetic resonance imaging (MRI) device, a two-stage cryocooler (42) employs a first stage cooler (52) to cool a working gas (e.g., Helium, Hydrogen, etc.) to approximately 25 K. The working gas moves through a tubing system by convection until the magnet (20) is at approximately 25K. Once the magnet (20) reaches 25 K, gas flow stops, and a second stage cooler (54) cools the magnet (20) further, to about 4 K.

主权项

1. A cryo-cooling system that facilitates passively switching between first and second cooling stages to cool a superconductor, including:
a first stage cooler; a first heat exchanger thermally coupled to the first stage cooler; a second stage cooler; a second heat exchanger thermally coupled to the second stage cooler; a down flow tube through which denser, cooled gas flows from the first heat exchanger down to the second heat exchanger; an up flow tube through which less dense, warmer gas flows from the first heat exchanger up to the second heat exchanger when the second heat exchanger is warmer than the first stage heat exchanger; and a superconductor thermally coupled to the second heat exchanger.