Regenerative expansion apparatus, pulse tube cryogenic cooler, magnetic resonance imaging apparatus, nuclear magnetic resonance apparatus, superconducting quantum interference device flux meter, and magnetic shielding method of the regenerative expansion apparatus

摘要

A regenerative expansion apparatus includes a regenerative tube configured to regenerate cryogenic cooling at the time of expansion of a coolant gas; a cylinder in communication with a low temperature end of the regenerative tube, the cylinder being configured to generate the cryogenic cooling by repeating compression and expansion of the coolant gas via the regenerative tube; a magnetic cold storage material filling inside the regenerative tube, the magnetic cold storage material being made of a magnetic material, the magnetic cold storage material being configured to come in contact with the coolant gas so that the cryogenic cooling is regenerated; and a magnetic shield member surrounding the magnetic cold storage material; wherein the magnetic shield member has an electric resistivity equal to or less than 50 muOmegacm at a normal temperature.